It is not in the german news hiechary. :) This mean it is no carries on all news servers.
de.* is also not carried on _all_ news servers. - I think we should know what we want to achieve.
If it is a discussion forum in german for GNU software then do that in de.comp.gnu.
If we want to cross-post this discussion (I think this makes sense) in a newsgroup I would choose soemthing like gnu.fsfe.discuss or gnu.eu.discuss.
It is not important if everyone carries these hierarchies. It is important that most do. :-)
AFAIK at least all major ISPs and news servers in Austria seem to feed gnu.* - I don't expect this to be different in other countries.