diff --git a/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/core_utils.hpp b/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/core_utils.hpp
index 9626d4940..cb7872dcd 100644
--- a/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/core_utils.hpp
+++ b/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/core_utils.hpp
@@ -12,7 +12,26 @@ namespace detail {
 
 template <typename Tuple, class Functor, std::size_t... Indices>
 constexpr void run_functor_with_tuple_index_return_void(Functor&& functor, std::index_sequence<Indices...> /*unused*/) {
-    (std::forward<Functor>(functor).template operator()<std::tuple_element_t<Indices, Tuple>>(), ...);
+    if constexpr (sizeof...(Indices) == 1) {
+        (std::forward<Functor>(functor).template operator()<std::tuple_element_t<Indices, Tuple>>(), ...);
+    } else {
+        (functor.template operator()<std::tuple_element_t<Indices, Tuple>>(), ...);
+        capturing::into_the_void(std::forward<Functor>(functor));
+    }
+}
+
+template <typename Tuple, class Functor, std::size_t... Indices>
+constexpr auto run_functor_with_tuple_index_return_array(Functor&& functor,
+                                                         std::index_sequence<Indices...> /*unused*/) {
+    if constexpr (sizeof...(Indices) == 1) {
+        return std::array {
+            std::forward<Functor>(functor).template operator()<std::tuple_element_t<Indices, Tuple>>()...
+        };
+    } else {
+        auto result = std::array { functor.template operator()<std::tuple_element_t<Indices, Tuple>>()... };
+        capturing::into_the_void(std::forward<Functor>(functor));
+        return result;
+    }
 }
 
 } // namespace detail
@@ -25,4 +44,9 @@ template <typename Tuple, class Functor> constexpr void run_functor_with_tuple_r
                                                             std::make_index_sequence<std::tuple_size_v<Tuple>>{});
 }
 
+template <typename Tuple, class Functor> constexpr auto run_functor_with_tuple_return_array(Functor&& functor) {
+    return detail::run_functor_with_tuple_index_return_array<Tuple>(
+        std::forward<Functor>(functor), std::make_index_sequence<std::tuple_size_v<Tuple>>{});
+}
+
 } // namespace power_grid_model::main_core::utils
diff --git a/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/main_model_type.hpp b/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/main_model_type.hpp
index 32ba2ca73..d86c3729f 100644
--- a/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/main_model_type.hpp
+++ b/power_grid_model_c/power_grid_model/include/power_grid_model/main_core/main_model_type.hpp
@@ -67,7 +67,6 @@ concept validate_component_types_c =
 
 template <class T, class U> class MainModelType;
 
-// TODO: discussion on checking dependent types can also be done here.
 template <class... ExtraRetrievableType, class... ComponentType>
     requires detail::validate_component_types_c<ComponentList<ComponentType...>>
 class MainModelType<ExtraRetrievableTypes<ExtraRetrievableType...>, ComponentList<ComponentType...>> {
@@ -111,11 +110,11 @@ class MainModelType<ExtraRetrievableTypes<ExtraRetrievableType...>, ComponentLis
     using ComponentFlags = std::array<bool, n_types>;
 
     template <class Functor> static constexpr void run_functor_with_all_component_types_return_void(Functor&& functor) {
-        (std::forward<Functor>(functor).template operator()<ComponentType>(), ...);
+        return utils::run_functor_with_tuple_return_void<ComponentTypesTuple>(std::forward<Functor>(functor));
     }
     template <class Functor>
     static constexpr auto run_functor_with_all_component_types_return_array(Functor&& functor) {
-        return std::array { std::forward<Functor>(functor).template operator()<ComponentType>()... };
+        return utils::run_functor_with_tuple_return_array<ComponentTypesTuple>(std::forward<Functor>(functor));
     }
 };
 
diff --git a/power_grid_model_c/power_grid_model/include/power_grid_model/math_solver/observability.hpp b/power_grid_model_c/power_grid_model/include/power_grid_model/math_solver/observability.hpp
index b73aac26e..985014837 100644
--- a/power_grid_model_c/power_grid_model/include/power_grid_model/math_solver/observability.hpp
+++ b/power_grid_model_c/power_grid_model/include/power_grid_model/math_solver/observability.hpp
@@ -94,8 +94,8 @@ ObservabilitySensorsResult scan_network_sensors(MeasuredValues<sym> const& measu
                 // we only need one flow sensor, so the loop will break
                 Idx const branch = element.idx;
                 Idx const neighbour_bus = y_bus_structure.col_indices[ybus_index];
-                BusNeighbourhoodInfo::neighbour const neighbour_info{neighbour_bus,
-                                                                     ConnectivityStatus::has_no_measurement};
+                BusNeighbourhoodInfo::neighbour const neighbour_info{.bus = neighbour_bus,
+                                                                     .status = ConnectivityStatus::has_no_measurement};
                 bus_neighbourhood_info[bus].direct_neighbours.push_back(neighbour_info);
                 if (has_flow_sensor(branch) && is_branch_connected(branch)) {
                     result.flow_sensors[ybus_index] = 1;
@@ -231,7 +231,7 @@ inline void complete_bidirectional_neighbourhood_info(std::vector<BusNeighbourho
             auto it = std::ranges::find_if(
                 reverse_neighbour_list, [&bus](auto const& reverse_neighbour) { return reverse_neighbour.bus == bus; });
             if (it == reverse_neighbour_list.end()) {
-                BusNeighbourhoodInfo::neighbour const reverse_neighbour_info{bus, neighbour.status};
+                BusNeighbourhoodInfo::neighbour const reverse_neighbour_info{.bus = bus, .status = neighbour.status};
                 reverse_neighbour_list.push_back(reverse_neighbour_info);
             }
         }
diff --git a/tests/cpp_unit_tests/test_observability.cpp b/tests/cpp_unit_tests/test_observability.cpp
index dd455b701..7e2279358 100644
--- a/tests/cpp_unit_tests/test_observability.cpp
+++ b/tests/cpp_unit_tests/test_observability.cpp
@@ -568,7 +568,8 @@ TEST_CASE("Test Observability - complete_bidirectional_neighbourhood_info") {
         // Initialize test data
         neighbour_list[0].bus = 0;
         neighbour_list[0].status = has_no_measurement;
-        neighbour_list[0].direct_neighbours = {{1, has_no_measurement}, {2, node_measured}};
+        neighbour_list[0].direct_neighbours = {{.bus = 1, .status = has_no_measurement},
+                                               {.bus = 2, .status = node_measured}};
 
         neighbour_list[1].bus = 1;
         neighbour_list[1].status = node_measured;
@@ -615,17 +616,18 @@ TEST_CASE("Test Observability - complete_bidirectional_neighbourhood_info") {
         // Bus 0 connects to buses 1 and 3
         neighbour_list[0].bus = 0;
         neighbour_list[0].status = node_measured;
-        neighbour_list[0].direct_neighbours = {{1, branch_native_measurement_unused}, {3, has_no_measurement}};
+        neighbour_list[0].direct_neighbours = {{.bus = 1, .status = branch_native_measurement_unused},
+                                               {.bus = 3, .status = has_no_measurement}};
 
         // Bus 1 connects to bus 2 (but not back to 0 yet)
         neighbour_list[1].bus = 1;
         neighbour_list[1].status = has_no_measurement;
-        neighbour_list[1].direct_neighbours = {{2, branch_discovered_with_from_node_sensor}};
+        neighbour_list[1].direct_neighbours = {{.bus = 2, .status = branch_discovered_with_from_node_sensor}};
 
         // Bus 2 has existing connection to bus 3
         neighbour_list[2].bus = 2;
         neighbour_list[2].status = branch_discovered_with_to_node_sensor;
-        neighbour_list[2].direct_neighbours = {{3, branch_native_measurement_consumed}};
+        neighbour_list[2].direct_neighbours = {{.bus = 3, .status = branch_native_measurement_consumed}};
 
         // Bus 3 initially has no connections
         neighbour_list[3].bus = 3;
@@ -700,15 +702,17 @@ TEST_CASE("Test Observability - complete_bidirectional_neighbourhood_info") {
         // Initialize with some connections already bidirectional
         neighbour_list[0].bus = 0;
         neighbour_list[0].status = has_no_measurement;
-        neighbour_list[0].direct_neighbours = {{1, has_no_measurement}, {2, node_measured}};
+        neighbour_list[0].direct_neighbours = {{.bus = 1, .status = has_no_measurement},
+                                               {.bus = 2, .status = node_measured}};
 
         neighbour_list[1].bus = 1;
         neighbour_list[1].status = node_measured;
-        neighbour_list[1].direct_neighbours = {{0, has_no_measurement}, {2, branch_native_measurement_unused}};
+        neighbour_list[1].direct_neighbours = {{.bus = 0, .status = has_no_measurement},
+                                               {.bus = 2, .status = branch_native_measurement_unused}};
 
         neighbour_list[2].bus = 2;
         neighbour_list[2].status = node_measured;
-        neighbour_list[2].direct_neighbours = {{1, branch_native_measurement_unused}};
+        neighbour_list[2].direct_neighbours = {{.bus = 1, .status = branch_native_measurement_unused}};
 
         // Test the function
         complete_bidirectional_neighbourhood_info(neighbour_list);
diff --git a/tests/cpp_unit_tests/test_y_bus.cpp b/tests/cpp_unit_tests/test_y_bus.cpp
index 8bf045956..0cc60aac6 100644
--- a/tests/cpp_unit_tests/test_y_bus.cpp
+++ b/tests/cpp_unit_tests/test_y_bus.cpp
@@ -434,13 +434,13 @@ TEST_CASE("Test counting_sort_element") {
     SUBCASE("Test basic sorting") {
         // Create test data: elements at various matrix positions
         std::vector<YBusElementMap> vec = {
-            {{2, 1}, {bft, 5}},   // pos (2,1)
-            {{0, 0}, {bff, 0}},   // pos (0,0)
-            {{1, 2}, {btf, 3}},   // pos (1,2)
-            {{0, 1}, {bft, 1}},   // pos (0,1)
-            {{2, 1}, {shunt, 6}}, // pos (2,1) - same position as first
-            {{1, 0}, {btf, 2}},   // pos (1,0)
-            {{2, 2}, {btt, 7}},   // pos (2,2)
+            {.pos = {2, 1}, .element = {.element_type = bft, .idx = 5}},   // pos (2,1)
+            {.pos = {0, 0}, .element = {.element_type = bff, .idx = 0}},   // pos (0,0)
+            {.pos = {1, 2}, .element = {.element_type = btf, .idx = 3}},   // pos (1,2)
+            {.pos = {0, 1}, .element = {.element_type = bft, .idx = 1}},   // pos (0,1)
+            {.pos = {2, 1}, .element = {.element_type = shunt, .idx = 6}}, // pos (2,1) - same position as first
+            {.pos = {1, 0}, .element = {.element_type = btf, .idx = 2}},   // pos (1,0)
+            {.pos = {2, 2}, .element = {.element_type = btt, .idx = 7}},   // pos (2,2)
         };
 
         // Expected sorted order: by row first, then by column
@@ -465,7 +465,7 @@ TEST_CASE("Test counting_sort_element") {
     }
 
     SUBCASE("Test with single bus") {
-        std::vector<YBusElementMap> vec = {{{0, 0}, {shunt, 10}}};
+        std::vector<YBusElementMap> vec = {{.pos = {0, 0}, .element = {.element_type = shunt, .idx = 10}}};
 
         counting_sort_element(vec, 1);
 
@@ -483,9 +483,9 @@ TEST_CASE("Test counting_sort_element") {
 
     SUBCASE("Test stability - elements with same position maintain relative order") {
         std::vector<YBusElementMap> vec = {
-            {{1, 1}, {bff, 100}},
-            {{1, 1}, {bft, 200}},
-            {{1, 1}, {shunt, 300}},
+            {.pos = {1, 1}, .element = {.element_type = bff, .idx = 100}},
+            {.pos = {1, 1}, .element = {.element_type = bft, .idx = 200}},
+            {.pos = {1, 1}, .element = {.element_type = shunt, .idx = 300}},
         };
 
         counting_sort_element(vec, 2);
@@ -510,7 +510,7 @@ TEST_CASE("Test counting_sort_element") {
             Idx const row = i / n_bus;
             Idx const col = i % n_bus;
             if ((row + col) % 3 == 0) { // Sparse pattern
-                vec.push_back({{row, col}, {bff, row * n_bus + col}});
+                vec.push_back({.pos = {row, col}, .element = {.element_type = bff, .idx = row * n_bus + col}});
             }
         }
 
@@ -535,8 +535,13 @@ TEST_CASE("Test counting_sort_element") {
 
     SUBCASE("Test all YBusElementType values") {
         std::vector<YBusElementMap> vec = {
-            {{1, 1}, {fill_in_tf, 6}}, {{0, 1}, {bft, 1}},   {{1, 0}, {btf, 2}},        {{0, 0}, {bff, 0}},
-            {{1, 1}, {btt, 3}},        {{2, 2}, {shunt, 4}}, {{1, 2}, {fill_in_ft, 5}},
+            {.pos = {1, 1}, .element = {.element_type = fill_in_tf, .idx = 6}},
+            {.pos = {0, 1}, .element = {.element_type = bft, .idx = 1}},
+            {.pos = {1, 0}, .element = {.element_type = btf, .idx = 2}},
+            {.pos = {0, 0}, .element = {.element_type = bff, .idx = 0}},
+            {.pos = {1, 1}, .element = {.element_type = btt, .idx = 3}},
+            {.pos = {2, 2}, .element = {.element_type = shunt, .idx = 4}},
+            {.pos = {1, 2}, .element = {.element_type = fill_in_ft, .idx = 5}},
         };
 
         counting_sort_element(vec, 3);