Using the alternation suffix in <rng:ref>s within <content> causes Roma to not create a corresponding RNG definition. The suffix alternation should trigger the generation of a <rng:define> wirh <rng:choice>, exactly as for the default behaviour.
See file dummy5.xml attached. This seems to show what you describe, and it compiles correctly. Can you supply a test file which does not work?
agreed this does _work_