@xjazzdummy After re-reading your wish… wouldn’t Scale per track on Play solve this problem? This wish has already 11 votes. And maybe the wish to push for is the ability to set scales per track, pattern and even variation.
This might be more complicated (?) not only to implement, also for users to handle. While it is true that it is common to apply different scales within a song, it is less common (I believe?) to apply different scales within a bar. If you are doing that, then you are probably adding chromatic notes to the scale, and if you want to do that, just disable the filter and add the notes as you wish.
Bottom line, maybe it is better to focus on Scale per track on Play and ask whether patterns and variations could be added there as well.