Ok this could get tricky depending on the info supplied .....
Technically, I think both pilots would have to be licenced to fly that foreign countries aircraft .. the instructor would have to be legal to fly as P1 and from the left seat. The candidate would have to then have at least a student licence of the country of registration of the a/c (and in that case the captain would then need to have an Instructor rating or approval to carry out dual training). That qualifies them to then be in the aircraft. Then the instructor (or if he has an ATPL and the candidate a CPL) can then do what ever training or checking he wishes for whatever other qualification he may have ????
Of course I may well be wrong!!!
Cheers