Proto-Brythonic sound changes

Are these accurate?

g vocalized to /j/ > /i/ before -n-, -r- and -l-
d vocalised to /j/ > /i/ before -n-, -r- and -l-
mb > mm
en[C] > in[C] > [ɨnC]
(INTERVOCALIC AND NEAR RESONANTS (/r/, /l/, /m/, /n/, /j/, /w/):
p > b
t > d
k > g)
ai > ē > oɨ
dg > dɣ
apocope: vowels (a e i o u j y) are lost word finally from Proto-Celtic to Proto-Brythonic. The suffix os or macron a is also lost.

If there's any I've missed/that are wrong, please say so! I'd be grateful.

CodeCat may know the answer to this, but Angr is our main expert on Celtic linguistics.

Ah right, thanks. By the way, this was brought up (again, without notifiying me... whatever...) on your talk page: I have added Aquitanian words to the site, but filed them under reconstruction, since their meanings are conjecture and reconstructed, and their etymologies too. However, the words have indeed been (though, latinised) recorded by the Romans. However, the Romans only wrote down names and Gods, so the words themselves are inferred from those names, and comparatively reconstructed or confirmed.