I suggest consulting Celtic mythology books in your language. Or Wikipedia.
You will find all the four tribes there with their names in your language.
For example, as far as I know, Tuatha should be pronounced as Tua, but in the Russian-language tradition it's Tuata. So that's what I call them in every-day speech. But in my translation for the game they will be Tua. With explanation given in brackets.
How do you pronounce:
(I'm German. Know nothing about Irish names.)