I think it may be rare to get another RFE, since they would probably address all the issues on the first RFE (that is, unless the evidence you sent back for your last RFE was insufficient). Since yours was just a simple translation of a birth certificate, I doubt it's related to that. I'm sure USCIS just messed up...yet again.
If USICS won't answer your question, then why don't you ask the person handling your biometrics appointment when you go in?
