Don't worry !

Only your state/neighbour states (they have agreement between neighbour states) has the right to access your driving history. But Canadian provinces also have agreement with US border states. Tickets are transferable between border provinces and states. Such as New Yorkers need pay fines to Ontario and Quebec. Canadian people also pay fines to New York State.

If you live in inner states like New Jersey, you are 100% safe.

Now US and Canada exchange our personal info for US Home Land Defence.
Our home addresses and birthdays are in Canadian government hands.

Yes, rental car will charge people for speeding no matter where you live. But this time is your car. You will get letters from a Canadian court in mail soon.

I live in Washington DC area, I have unpaid Canadian tickets for years but I still can enter Canada many times (include last weekend) without any problems.

Next time in Canada, drive another car and let another driver to drive. Don't let them catch you again.