I think a huge separation between the German and English forums (like separate sites) is NOT the way to go. There are too many people who can manage in both languages (at least reading), and information will be missed by everyone who would like to check both fora.
Reality = the dev team are mostly German. Reality = they will be most comfortable with discussions in German. Let them be comfortable -- there is no reason to hide the German forum from English speakers.
However, titan is correct about the majority language for Internet conversations -- it is indeed English. So siduction must have a living English forum, and it must be attractive, especially for folks who are not confident of their ability with Linux, much less their ability with English. Anyone who has caught a "RTFM" between the eyes knows not to ask any more questions at that place.
I would even go so far as to suggest a "Noob Corner" forum, for those who know they don't know. While Debian Sid is not a recommended branch for noobs, this siduction distro is a very reasonable choice for someone bored with Ubuntu and ready to learn more, IMHO. We should welcome such users, and let them know it's OK to ask a question that might seem noobish. I would personally be willing to help with their issues, to the limits of my limited ability.
/stump speech