I've worked with certifications in Canada and in the U.S.
In my experience, obviously the country where the airplane is being designed is the lead in certifying the airplane. I don't know exactly what the laws are, but usually the FAA and EASA are involved if it's in Canada.
There are periodic familiarizations. Those usually happen at a very high level, and Transport Canada will explain where they are in the process, what the airplane is like and so on. I think at that point they do have an opportunity to say that they've had issues with something, they're concerned about a regulation, and they want to dive into that.
That would have to be verified, but I'm pretty certain they do have an opportunity to do that. It's just not done very often because there's a really good reciprocity agreement.