"Presidente Alcazar"
Anybody who flew RAF aircraft underwent an RAF training course. Even
the first Eagle squadron volunteers did so in the winter of 1940.
Transfer into the USAAF from the RAF was voluntary for American
pilots, and some didn't want to do it, for various reasons (in one
case a sense of obligation to the RAF who had paid for his training
and posted him to a combat unit where the pre-war USAAC had rejected
him as a pilot, another because he throught he'd fail a more stringent
USAAF medical examination). However, most did, for various reasons -
the most common given being for the higher pay.

I expect all newly recruited pilots/aircrew would take training whether
they enlisted by coming up to Canada or going directly to Britain regardless
if they were trained. They would need some sort of conversion training.
In Canada this was done by the British Commonwealth Air Training Plan.
Canada was considered the training airdrome for the British Commonwealth.
They trained aircrews at many stations spread across Canada. Most wanted to
be pilots but the greater majority ended up as Navs, Air Gunners, Wireless
Operators and Bomb aimers eventually assigned to No. 6 Bomber Group
(R.C.A.F.).
Ed