Noun determiner choice validation logic

Currently for nouns in the Lexicon, parent’s choice for determiner is only considered by the validation code if it is “impossible” or “obligatory” (but not “optional”).

As a result, I get a validation error when I am trying to have my nouns inherit the “optional” constraint from a parent.

Is that intended? Is there something wrong with trying to inherit “optional determiner”? If so, I could change the validation message or something. If not, I can fix the validation code, but it seems unlikely that nobody has encountered this before.