Yes, he was a native speaker - and under his direction the CO version of the Bible was translated.

Or maybe it means WTF?

240 - 242

ag cur an mhilleáin ar gach éinne eile sa tigh 'blaming everyone else in the house'
tréad 'flock, herd'
dallamullóg 'blindness, confusion'

_________________
I'm an intermediate speaker of the Corca Dhuibhne dialect of Irish and also have knowledge on the old spelling
Soir gaċ síar, fé ḋeireaḋ thíar

243 - 246

ceartlár 'very centre'
ó a dó, normally this would be óna dó, with eclipsis on the numeral particle. Oftentimes however, prepositions ending in long vowels don't trigger mutations on following vowels in CDh where they normally would in the standard
fiaclóir 'dentist'
léitheoir 'reader'
beathaidh dative of beatha, with the genitive beathadh
giuirléid 'implement'
prionsúir 'pincers'
anéistéiseach 'anesthetic'
bireáinín does anyone know what this means?
muinntir mo chéile 'my in-laws'

_________________
I'm an intermediate speaker of the Corca Dhuibhne dialect of Irish and also have knowledge on the old spelling
Soir gaċ síar, fé ḋeireaḋ thíar

N in óna isn’t really eclipsis. It is just formed analogous to ina (which is really due to eclipsis i n-a).
Ó a dó is the older form (pronounced "ó dó"), "óna dó" is an innovation.

bireáinín - could this mean little pin?

That would definitely make sense, I should have realised that sooner

_________________
I'm an intermediate speaker of the Corca Dhuibhne dialect of Irish and also have knowledge on the old spelling
Soir gaċ síar, fé ḋeireaḋ thíar

247 - 249

ní chuala riamh focal eatarthu i bhfearg 'I never heard an angry word between them'
bronntanas pósta 'wedding gift'

_________________
I'm an intermediate speaker of the Corca Dhuibhne dialect of Irish and also have knowledge on the old spelling
Soir gaċ síar, fé ḋeireaḋ thíar

250 - 252

an cine gorm (contemptuous) 'the negro race'. when referring to people, gorm (which is literally a deep blue or green) translates to 'black' in English, e.g. fear gorm 'a black man'
an bunstoc 'aborigines', literally 'original stock'
duine a chur i bponc 'to perplex someone'
bundúchasach 'anborigine'
iargúlta 'isolated'
bástáil 'basting'

_________________
I'm an intermediate speaker of the Corca Dhuibhne dialect of Irish and also have knowledge on the old spelling
Soir gaċ síar, fé ḋeireaḋ thíar

No. Fear gorm is not contemptuous. Americans are constantly pushing race grievance. When I lived in China, I met Americans who were determined to claim racial victimhood status for themselves in China, because foreigners are called the innocuous term laowai in China (lao, old; wai, foreigner; this is not contemptuous as the use of lao shows respect, e.g. someone called Wang in China can be called Lao Wang).

Fear gorm is in fact Connemara Irish (not contemptuous) for a black man. Fear dubh is the correct Munster Irish.

Cine should be feminine in Munster Irish: an chine dhubh.

Cnósach Focal ó Bhaile Bhúirne has ráigiúnach for a non-white foreigners (but bear in mind that before a few years ago there were virtually no such people in Ireland, and this has not been a traditional faultline in Irish culture, no matter how much Americans will push this agenda).