Totally agree that everything posted in Mandarin (or any other language, except for the German forum which is set up for that purpose) should be translated/glossed. (And use proper Pinyin while yer at it...but that's another issue.
In the Learning Chinese forum, at least, I think we have been fairly consistent about asking people to translate or going back in and "helping" with translations or Romanization. It's in our forum sticky rules (not that anyone reads THAT...) Hopefully other forum mods will agree. If there's something of the short-comment variety that needs translating and the mod can't do it, they need only PM one of us.
The "report" button would also work -- no need to report a cataclysm, just say there's stuff that needs to be translated. But posters who know enough to post in Chinese should have enough courtesy to help the community understand what they're posting, IMO.