“Wrong” “not in abstract” warnings.

[WolframKahl]

With the six source files appended below, with concrete C_T of C, with both 3.10 and 3.10.4 I get, rather unexpectedly:

> i --retain C_T.gf
- compiling A.gf...   write file A.gfo
- compiling C.gf...   write file C.gfo
- compiling Iface.gf...   write file Iface.gfo
- compiling A_I.gf...   write file A_I.gfo
- compiling Instance.gf...   write file Instance.gfo
- compiling C_T.gf... 
C_T.gf:
   Warning: category CC is not in abstract
   Warning: function XX is not in abstract
   Warning: function ZZ is not in abstract
  write file C_T.gfo

The categories and functions that these warning messages complain about are the categories and functions of C.

The resulting dependency graph is:

It seems that the arrow from C_T to C is of the wrong kind --- is that an explanation for these warnings?

And I get:

> gr
linking ... OK

Languages: C_T
Category S is not in scope
CallStack (from HasCallStack):
  error, called at src/compiler/GF/Command/Commands.hs:881:38 in gf-3.10.4-CzxgA2HFjlY9VSzSmw6B1W:GF.Command.Commands

(And the language C_T seems to be competely unusable.)

Here are the source files:

NotInAbstract-2021-03-05.zip