Well, it's less detrimmental than not being able to voice a FR or comment because of not speaking or reading english well.
In case of FR or bug reports, the subforum can serve as a help to find an english description of the issue that can be brought over to the english forum (and back to the non-english if needed). In case of people searching for help the advantages are obvious.
EDIT: Ah, yeah. As that other Kraut above me just said.