If Wolfe didn't use his chest to play musket ball catch, we wouldnt be having this conversation. Quebec would have become England like the rest of the Empire and the idea that Canada is "special" would have died on the cutting room floor well before 1867.
the BNA in 1867 was the means to an end for a British Parliament that had other pressing issues to address (keeping India British was a full time job). The Constitution Act of 1982 was merely PET compromising his Republican wants with the realities of being a Westminster constitutional monarchy. It brought some power to address Canadian identity, while preserving our democratic institutions.
Nowhere in this exercise was there a belief or desire from the monarch to have a separate "crown" for Canada. As far as they're concerned, and rightly so, we did not sprout up out of nowhere. We were conquered, developed, and grew within the Empire to become the nation we are today. To develop a "Maple Crown" denies that role in our history.
The diadem is a separate issue because it isn't a mark of authority within our heraldry or history. It's a Canadian, stylized version of the George IV Diamond State Diadem that, again, has actual significance and history. It also, again, is a real, tangible item and not a paper crown.
I don't know why we have such a chip on our shoulder about this kind of stuff, but we are part of the club... no need to copy someone else's homework all the time to make us feel better about ourselves.