On one hand, I'm all for more authenticity. But I can't help thinking that this change will greatly annoy me because proper Celtic names that are already in the game (Irish, Welsh and Breton to a certain extent) are often utterly incomprehensible to me. I don't think I'd be playing as Scotland nearly as much if their names were "gaelicized".
I agree, I have a hard enough time deciphering the names, but just try saying them out loud. No really, look around and make sure you are alone. OK, now say
mac Donnchada. It's alright, I don't know how to pronounce it either, just say it again like you mean it.
MAC DONNCHADA. There you go, now you are a Scotsman.
Being able to sit around and do this during a game of CKII is a major quality of life improvement for playing Scotland.