Managed to skim through the recordings. A few notes:
Stairs bro: Interesting alternative solution which I'd argue is trickier than the intended one.
Merge Sort: Interesting to see you struggle, and somehow finding a solution without fully understanding why it works. There's a key observation about merging (which I thought was obvious, but seeing different people struggle I guess it's not) which, once realized, makes it very clear where and when to place the miners.
Downpour: Used to have timed bombers, so I set the requirement low to make the level not too annoying. Now with instant bombers, it's quite trivial so maybe the save requirement could be raised a bit.
Impetus, Prelude, Lix Cannon: Look like backroutes?
I agree with your assessment that Lovely and Quirky contain some levels which seem too complex for the rank, and maybe it'd have been sensible to make these ranks a bit easier than their are overall. For example, Lovely could contain a few more levels with small skillsets that reinforce the behaviour of certain skills (like Beneath the Lab reinforces that builders turn while platformers do not).
Time to change the road: Used to have a time limit, enforcing a specific idea. Now it's easier, so I think it could be moved down to Lovely. (Could also fix it enforce my initial idea, but in line with the assessment above I'd also support the simple downrank).
100 ways to die: Should this maybe go into Lovely as well?