I have 2 projects with names "UdfProject" and "new".

I have a view model in UdfProject which includes a view model with UDF function (procedure). The procedure has property "relational:Function Category" set to TEST_FUNCTIONS.

When I create a view model in project named "new", add a table and use Expression builder in transformation SQL, I can see the function category "TEST_FUNCTIONS" here. (See screenshot)
I think it doesn't make sense to have this option here (in different project than the one that includes the jar).