I don't see how it matters, the game is sometimes won by luck although of course it pays to have good command of the English language. I play quite regularly with family members and we remember the value of tiles off by heart. Changing them would achieve nothing in our opinion. (I've just had a show of hands).
I am just wondering is the game played in other languages? I don't fancy taking anyone on in Mandarin or Russian.
Are the tiles of different values in German? If it is played in Germany that is.