Had an interesting one on one conversation with a guy who works in one of those FSDO's.
Much to my surprise he came up with two nuggets....for the issue of a temporary certificate (and eventual FAA licence) based on a foreign licence EITHER an FAA medical OR the relevant foreign medical needs to be current. He said that you do not eed both, nor do you NEED an FAA medical if your foreign one is current.
Second nugget was that provided you foreign licence was VALID it didn't have to be CURRENT. When asked to explain, he said provided that the foreign licence had not been terminated for any reason, it was still (in FAA terms) a VALID licence - and the TAC issued on the strength of it would become both valid and current when passing the BFR with the rental school.
He said the foreign licence DOES NOT have to be current....just valid.