Fòram na Gàidhlig

If these were Scottish Gaelic names – I know they aren't, but let's assume they were – how would you pronounce the names Coibean and Coibheantìn. With the help of Wikipedia, I constructed the following pronunciations. Are they correct?

Coibhean /kʰovən/
Coibheantìn /kʰovəntʲʰi:n/

I'm especially unsure whether the <oi> will be pronounced open /ɔ/ or closed /o/, whether the <ea> is pronounced mid-front /ɛ/ or mid-central /ə/, and whether the <t> is aspirated and where (pre- or postaspirated).

You're pretty close, but the answer is "neither". I'd for /ɤi/

Coibhean /kʰɤivən/
Coibheantìn /kʰɤivənˈtʲʰi:n/

The second name violates the spelling rule, and also Gaelic stress which is always on the first syllable (unlike Irish). you could go for Coibheintin or Coibheantan instead.

Thank you, GunChleoc.

Like this?
Coibheintin /kʰɤivəntʲʰin/
Coibheantan /kʰɤivəntʰan/ (or /...ən/ ?)

Oh, and how would I spell the name if I wanted it to be pronounced /kʰovən/? Cobhan? But that would be pronounced /kʰo.an/, wouldn't it?

Transcriptions are correct. The bh used to be pronounced historically (which is why "Inbhir Nis" is "Inverness" as pronounced by English speakers, with a v), but in the modern dialects, it gets dropped.

Thank you for your kind help, GunChleoc.

'S e do bheatha