Do we want to have gendered nouns/adjectives?
Maybe some kind of noun classes that aren't tied to gender?
That seems a good idea
Based on the words we have so far, I think the three options should be "-is" nominatives, "-ez" nominatives, and "-in" nominatives
How should those decline, then?
Tbh, imo, "-is" and "-ez" are far too similar sounding to really support different sets of inflections over a longer period.
are they though? remember also that final "-is" would be a stressed syllable and final "-ez" would be an unstressed syllable