Following the advises of of Alex Fink, I've revisited the phonology of
Proto-Yanyarin. As before, the collection of consonants that the speakers
of Yanyarin and can pronounce is limited almost entirely to labial to
labio-dental and from uvular to glottal. I have moved the existing sounds
more towards the glottis, so that the sound inventory looks more suited for
a "species with a weak tongue that always sing". The orthography was also
changed, mostly for the sake of eughraphy.

The chart includes:

m             n
b              g   q   '/?
w   d         j    x   h
     s               l   r
m ~ [m]; n~[ŋ]; b~ [b]/[ʙ], g~[ɢ], q ~ [ʡ], '/? ~ [ʔ], w ~ [β], d ~ [ð], j
~ [ʁ̞]/[ʕ̞], x ~ [ʢ̞], s=?, h ~ [ɦ], l ~ [ʀ]/[я], r ~[я]/[glottal thrill]

I don't know the precise value for ⟨s⟩ by now. The sound depicted by this
letter would not exist in "modern" Yanyarin, and in some point ⟨s⟩ has to
transform into ⟨r⟩ and ⟨d⟩. The voiced glottal thrill is one of the
nonhuman features of the speakers of Yanya.

In Proto- and modern Yanyarin there are 8 vowels:

i,y          v,u

The main difference of vowel chart form to normal one is that closedness of
the vowels is replaced by pharingealization. This is why I'm not able to
write this chart in the IPA right away. It is worth saying, however, that
in this notation v ~ [ɨ].

Finally, I'd like to have schwa, "schwi" and "schwo" sounds on several
stages of Old Yanyarin and Middle. I haven't decided on the signs for them,
but presumably ⟨z⟩ and ⟨c⟩ would be used for two such sounds. However,
maybe it's better to use IPA for clearness, since this sounds won't be in
use in modern Yanyarin.

Thanks for reading! Any suggestions? What am I missing? And thanks again!