PeachMan , 9 months ago

It looks like Mozilla doesn’t maintain an official Canadian dictionary, they just rely on this add-on created by a single guy: …mozilla.org/…/canadian-english-dictionary/

I’d suggest turning that dictionary off and relying on a third-party spelling/grammar app with better Canadian language support. I don’t know if they have a Canada-specific option, but I like LanguageTool: addons.mozilla.org/en-US/firefox/…/languagetool/

There are a lot of options out there, be careful about which ones have a decent privacy policy. Keep in mind, they could easily record anything you type, on any website.