Hello, the CRUD is currently not supported on all the SWIS entities. The list of the entities, which fully support the CRUD you'l get by query
SELECT FullName, CanCreate, CanRead, CanUpdate, CanDelete FROM Metadata.Entity where CanCreate = 'True' and CanRead = 'True' and CanUpdate = 'True' and CanDelete = 'True'
and analogically filter it per your needs.
Hope it helped.
I'll check it