diff --git a/python/sdist/amici/sim/sundials/_numpy.py b/python/sdist/amici/sim/sundials/_numpy.py
index 3e254db175..50a9c5de92 100644
--- a/python/sdist/amici/sim/sundials/_numpy.py
+++ b/python/sdist/amici/sim/sundials/_numpy.py
@@ -65,6 +65,15 @@ def __getattr__(self, name: str) -> xr.DataArray:
         if data is None:
             return xr.DataArray(name=name)
 
+        if isinstance(data, float):
+            return xr.DataArray(data, name=name)
+
+        if not isinstance(data, np.ndarray):
+            raise TypeError(
+                f"Cannot create xarray DataArray for field {name} of type"
+                f" {type(data)}"
+            )
+
         dims = None
 
         match name:
@@ -90,7 +99,8 @@ def __getattr__(self, name: str) -> xr.DataArray:
                 coords = {
                     "time": self._svp.ts,
                     "free_parameter": [
-                        self._svp.parameter_ids[i] for i in self._svp.plist
+                        self._svp.free_parameter_ids[i]
+                        for i in self._svp.plist
                     ],
                     "observable": list(self._svp.observable_ids),
                 }
@@ -111,11 +121,12 @@ def __getattr__(self, name: str) -> xr.DataArray:
                 coords = {
                     "time": self._svp.ts,
                     "free_parameter": [
-                        self._svp.parameter_ids[i] for i in self._svp.plist
+                        self._svp.free_parameter_ids[i]
+                        for i in self._svp.plist
                     ],
                     "state": list(self._svp.state_ids),
                 }
-                dims = ("time", "free_parameter", "state_variable")
+                dims = ("time", "free_parameter", "state")
             case "sllh":
                 coords = {
                     "free_parameter": [
@@ -153,6 +164,15 @@ def __getattr__(self, name: str) -> xr.DataArray:
         )
         return arr
 
+    def __dir__(self):
+        return sorted(
+            set(
+                itertools.chain(
+                    dir(super()), self.__dict__, self._svp._field_names
+                )
+            )
+        )
+
 
 class SwigPtrView(collections.abc.Mapping):
     """
diff --git a/python/tests/test_swig_interface.py b/python/tests/test_swig_interface.py
index c2823228ab..370f82d9fa 100644
--- a/python/tests/test_swig_interface.py
+++ b/python/tests/test_swig_interface.py
@@ -594,6 +594,15 @@ def test_rdataview(sbml_example_presimulation_module):
     assert (xr_x.coords["time"].data == rdata.ts).all()
     assert (xr_x.coords["state"].data == model.get_state_ids()).all()
 
+    # test that generating the xarrays does not fail, without checking
+    #  their content any further
+    for attr in dir(rdata.xr):
+        if not attr.startswith("_"):
+            try:
+                getattr(rdata.xr, attr)
+            except TypeError as e:
+                print(str(e))
+
 
 def test_python_exceptions(sbml_example_presimulation_module):
     """Test that C++ exceptions are correctly caught and re-raised in Python."""