Medical required just the once
@clearbluesky, you are right, if you hold a Canadian RTR, then a direct conversion is possible without any exams. I got mine converted initially for 3 years and now renewed for 20 years. Could you shed some light on the validity of the Canadian CPL, I doubt the license itself expires.
From what the current practice goes, they require the Class -1 Medical of that country to be valid for the issue of the converted license. I do not think it is required to be current after that. Nowhere does it say that. For that matter, to exercise privileges of your Canadian license, I'm pretty sure there are several other things that are also required (currency, rating-specific recency etc), but that doesn't seem to be required!