It's more than just Irish or Welsh. We wouldn't do the beasties such a dishonor as to just give them any Irish or Welsh name, you have to make up for them not being Scottish after all.
We did have mostly GĂ idhlig names for a long while, but with more keepers here not speaking it, the paperwork turns into a mess. There are only so many times you can try and correct how someone spells Flaithbheartach.