Generally it is a bad idea to use common words from common languages for character names, simply because so very many other players may be from around the various language-speaking countries (Germany, by the way, being a very prominent one). And it tends to be awkward to roleplay with someone who goes around calling him- or herself Frog. The fact that you have used this name for such-and-such time in such-and-such places is irrelevant. If you\'ve also read the rules for naming, you might know that making threads discussing GM decisions is not a good idea :) You are free to dispute the actions of the GM who changed your name either with that GM, or with another (or on IRC - server freenode, channel #planeshiftgm-talk), explaining why your character needs to be named the way he or she is. PlaneShift is generally an English-based game, with other languages best used on private channels rather than in the public, so a common word in a common language tends to push other (in this case numerous German) players into an out-of-character realm.
Anyway, my take on it :) Please continue the discussion with more appropriate authorities. If anyone believes that he or she has something truly significant or different to add, PM me and I will reopen the thread.