Does anybody know if there is an international review board (like TER)?

Yes , it's called TER ! Or as NY Magazine calls it: "TheEroticReview.com, the sex-for-hire industry’s Bible blog"

You can look up TER's definition in the dictionary. (Attached link, A John's Lexicon)

TER covers UK, Canada and South America (TJ) as far as I know, however you can always post a review of an escort in another country. The problem is that most escorts out of US, (East Asia, Middle east, East Europe, ..) do not have online advertising, and without a valid link they can not be reviewed... Also while TER head quarters are in Amsterdam, hobbyists and providers in Amsterdam could not care less about reviews since it's legal there and no review can take the place of Red light districts windows!!

Rumor has it that TER Empire is expanding to East Asia with theeroticreview.asia ....And theeroticreview.mobi will be soon available for your cell phones!!!

I don't know of any other site which covers both national and international escort reviews as much as TER does.

Not exactly like TER, but there are a few. ISG and club hombre to name a couple. I'd post a link, but I doubt it is allowed.

PM me if you'd like.