What in god's name is going on with my phonology?

Can we finally motivate our diphthongs? We're doing short-vowel "breaking" à la Sámi:

a > ea as in ase > easi, kata > keata, but katu > katu, harma > harma
i > ie always, but serme > sermi

Something about blocking in polymoraic syllables?

o > uo as in coro > cuoru
o > oa as in koli > koali

We need to figure out the context rules, and also whether /i/ and /u/ change. i > ai, u > au, maybe?

So one isogloss thing between dialects could be whether/when these things happen. How about E/W/Capitol all do it (but ever so slightly differently), but N doesn't?

SO, how do we motivate long diphthongs? Do we have palatalized consonant phonemes in modern Seadi? We've been paying too much attention to orthography instead of phonology.

Is it possible that the short/long vowel distinction is being neutralized in southern dialects of Seadi in favor of quality differences? If /e/ never appears stressed in open syllables, but /ē/ does, it's a prime opportunity to lose the length feature since it's no longer contrastive.

But Jesus, this is going to mean a ****load of paradigmatic leveling with both verbs and nouns.