Tá bonn tíreólaíochta na bpobal GAelach teoranta d'Innse Gall...

This is also from Cómhar. Limited to the Hebrides. I can't find teoranta do in dicitonaries. Is this good Irish?

Níl a fhios 'am.
Ach de bhrí's go bhfuil "cuir teorainn le" ann déarfainnse freisin: "teoranta le".

Thank you, Labhrás, I believe you are right on that!

I saw the rest of the paragraph online.
It sounds a bit stilted to me.

Thank you. I think any version with teoranta there will be unnatural. Also I think pobal Gaelach is a bit odd - I mean are the Gaeltacht people the only Gaels in Ireland? Or are English speakers also Gaels?

Surely being of Gaelic descent, as signified by a surname with ó or mac or ní or níc - makes you a Gael, even if you don't speak irish?

Bonn tíreólaíochta may also be Béarlachas (geographical base? geographical footprint?)
Maybe this should be:
Is iad teórainneacha tíreólaíochta pobal na Gaelainne ná Ínse Gall.....

Bonn tíreolaíochta - yeah it sounds unnatural. A direct translation from English.

I would just say "ceantair" (regions).