French vs Canadian Masters' is a very subjective call I think. I used French to improve my score from 458 to 474 at the age of 34. But not everyone is comfortable learning a new language - it's an entirely different skillset from comprehending a STEM course for example. And I had a backup plan of enrolling in a 1-yr masters' in Canada in case French didnt work out. It would have been a second masters' for me, but I would have used it to pivot to a different industry that I was always interested in. Plus, it would make one more employable in Canada as well (as would French), considering the network one can build during a good masters' course and the particularly local nature of Canadian industry (higher value given to reputable local universities than to much more reputable foreign ones). 12 months is hardly a long duration and it would have been a nice break from work.
So there's no one size fits all solution here. Just make sure that if you do choose to do a Masters', you do it from a reputable university. Doing it from an immigration oriented fly by night operator is a recipe for disaster.
Ultimately, choose the path that suits you. But certainly don't sit by waiting for the score to drop below 469 - that seems unlikely.
Edit - One further aspect regarding masters' courses - universities in Quebec are largely subsidized by the Quebec government. Many courses are not expensive for even international students and you get a chance to immerse yourself in a francophone culture during your studies. So it might help you both ways. So check that out if you are looking for cost effective masters programs.