Tbh, imo, "-is" and "-ez" are far too similar sounding to really support different sets of inflections over a longer period.

Tbh, imo, "-is" and "-ez" are far too similar sounding to really support different sets of inflections over a longer period. What you could have though is the nominative ending's grade of voicing influencing case inflections, so, idk, have a nominative in "-ez" turn the genitive (?) ending "-x" into "-g" or "-r" or whatever we would agree upon as a voiced equivalent to "x" (since the obvious option "ɣ" doesn't exist here).

Phonological inventory looks fine to me, don't you think though that all three of /b v w/ might be a bit much? Very few languages other than English have all three, and if our language is spoken, I'd assume most dialects would simplify to two or even just one forms ( just /β/ and /w/ for example).

Secondly, for the romanisation, why not take "x" for the sh-sound and "c" (or "ch") for the ch-sound? X for sh is common in many natural languages (Catalan, some South American Indian languages...), while I have never seen c for sh, tbh.

Stuff still going on here, people?

Name: Cranberry
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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?

Maybe some kind of noun classes that aren't tied to gender?

Do we want to have gendered nouns/adjectives?