So it would be nice to can customize any block by writing a template path on Sonata Admin, for example a SimpleBlock now needs to edit CmfBlockBundle:Block:block_simple_createphp.html.twig
(or without createphp) in order to customize a simple block, but it will affect every SimpleBlock
which sometimes is necessary to have independent templates...
I don't know if this feature exists, to change template of a single block, but I've not found it unfortunately.