I'm really impressed by how fine-tuned your ears are... able to tell between different areas of Ontario? To my ears (and I've traveled all over the continent) there are basically two different Anglo accents that I can really distinguish in North America, U.S. deep south (found from east TX to the Carolinas, mostly outside cities), and North-American-non-U.S.-Southern. (Includes all Canadians... oh, actually not Newfoundlanders any more, now that I've heard videos, thanks SHH
)
Having said that, I can immediately and effortlessly tell a Saguenay accent, even more easily a Gaspésie accent, and it's easy to tell from which area of France someone comes based on the accent (and if Belgian or Swiss instead), so I suppose that your amazing skills (to me) are just normal. I can actually even recognize a Sorel-specific accent, but the kids nowadays have of course zero accent, only people 50/60 or older, more or less. I think people my age and younger from southern Quebec don't really have regional accents any more.
I wonder how long it takes to develop that ability to recognize and identify ridiculously small differences in accent if you're not a native speaker... it's likely the very last thing you develop... or maybe never?