Consonant allophones in Minza

In the latest update to the Minza phonology, I've decided that the
retroflex and post-alveolar consonants are allophones; retroflex when
adjacent to back vowels, and post-alveolar next to front vowels. Along
with this change, I'm introducing at least one and possibly up to three
new vowel distinctions. (A single consonant between two vowels belongs
to the following syllable, so its allophone is determined by the
following vowel). Additionally, the velar consonants have palatal
allophones. Now, there are a couple of issues with this:

For one, although it's technically possible to have post-alveolar nasals
and laterals, it seems like it would be hard to make the three-way
distinction between alveolar, post-alveolar, and palatal. Minza doesn't
have a velar lateral, but older versions of Minza do have a velar nasal,
and I'd originally planned to reintroduce it. One possibility is that
the velar nasal only occurs next to back vowels.

The other thing is a writing issue: how to spell a sound that alternates
between [G] and [j\], similar to what happens in Modern Greek. I've been
writing this phoneme as "j", which works fine in words like "jönžix" (to
rain), where it represents [j\]. But I don't like how it looks in words
like "jovi" (excessive, too much). Another possibility is a "gh"
digraph: "ghönžix", "ghovi", or some kind of "g" with a mark over it:
"ġ" or "ğ". I could use just plain "g" if I didn't already have a /g/
phoneme. Certainly there are precedents for languages using "g" to
represent /j/, so that might be the best alternative. Or just pick some
unused letter like "q", but I can't find anything that's even as
suitable as "j".

For the vowels, it's tempting to use a diacritic for all front vowels:

Front: ï ë ä ö ü
Back:  ı e a o u

But then one of the most common vowels would be ï and there'd be dots
everywhere. Well, more dots than i's normally have.... At the very least
I'll likely be adding an /ä/ vowel; /ö/ and /ü/ are possible but
marginal additions. In any case, with all these marks over both the
vowels and consonants, it might look better to just use digraphs for the
extra consonants.

Another possibility which might look nicer is to use dots under the
letters for back vowels.

Front: i e a
Back:  ị ẹ ạ o u

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