Thanks for your reply. I have set the locale now, and that solves at least this problem.
German locale should be using the iso-8859-1 (or rather iso-8859-15) charset, which does contain an e with umlauts. Standard French language doesn't have umlauts, but Dutch (my native language) does. Either way, all Western European countries use the same charset, which should be iso-8859-15 (that's latin1 plus euro).
The problem now is that I don't know which charset will be given to me in the request... Could be pretty much anything.