How does language alter the game? For example if I buy Spanish instead of English. Are there a lot of cards with text that are being altered? Or is it only the manual and game box text that changes?
The only in-game text is the names of the shows on the tiles. It's not incredibly important, and they are also coordinated by numbers on the reference sheet. You'd probably be okay, although you may want to translate the names of the shows for thematic purposes.