There are quite a lot of exercises on Duolingo that include the pronunciation of uaithi or uirthi.
Unfortunately, the current speakers pronunciation of uirthi is very inconsistent - I hear 4 different pronunciations.
(Donegal Irish tends to pronounce the 3rd person feminine prepositional poronouns with an "ee" ending, Connacht and Munster are more likely to use an "eh" or "uh" sound).
Sorry I didn't see all your links when I first commented. I must say it is a little depressing to be trying to learn a language and never have a definite way of saying a lot of the words. And I understand that not everyone pronounced words the same in Irish but they don't in English either but when you learn English you really do have a standard to go by. I feel like one day (years and YEARS from now, lol) I may be able to read Irish but never really understand it spoken,,,,oh well, who knows, maybe if I watch enough Irish shows on TG4.....