If importing from OSM (or Wikipedia) it would seem sensible to only accept content that has remained unedited for the last X hours. If something has been staple for a couple of days, it's probably not outrageous vandalism.

You'll still need some way to deal with ongoing edit wars -- I'd imagine the mapping of Jerusalem to be prickly, for example. But at least you can tell that content is dangerous and direct your human review in that direction.