The idea of a system to choose language (or generate easily a translation) is not bad. But:
1. is probably a lot of work to put in place a such system.
2. if you have your firmware in other language, is more complicated to help you or follow the documentation
Don't forget you have the source code and you can translate the web interface yourself (I think ...)
Sorry for the answer in english, I'm french too. But in this communaute we are a lot of non-native english and if we want communicate, we need to have a universal language.