Is [triple-counted paper ballots] a prevalent concept in Canada?

Yeah, it is. Because it works really well.

The way I see it cryptography researchers already figured out the math to make electronic voting safer than paper

No, it's not. And the math isn't the problem. Our paper elections have scrutiny like open-source code, and voting machine code does not. Issues are spotted at vastly different rates, and not how you'd think without understanding the workings of both.

Also it's far, far less expensive to set up a polling station. We can do it in a morning, run an election all day - one day - and then shut it down after the count and we're out of there.