Honestly thats a semi believable part of the bible. Hear a language enough and ya kinda start to get ahold of it. Mind you it requires a base to work with, but given the whole Rome thing I suspect ya could pick up quite a bit at a market or port. Hell Ive experienced it myself, ive on multiple occasions have read Dutch or a Nordic language only to realize I dont know said language and promptly cant read it anymore.

I also watched a Dutch candle making video, that was a weird day overall though.