alright this is awesome so I'm gonna try to talk through everything I could think about
Conceptually I think there's crazy potential with this, I especially liked how the audio actually reflected the harmonics being tuned to the music, it's a very nice detail that I think carried my enjoyment throughout, also the adaptive music across the chapters was a really nice touch
Personally I'm a little sensitive to panned drums, I think especially for this kind of edm you want your drums to be very front and center, this kinda felt like one of those 8D rotating music videos and it felt a little gimmicky (but maybe that's just me, also maybe it's supposed to leave space for the sine waves, I can't complain if that's the case)
otherwise the music is really good
As many have pointed out the controls did feel a little confusing, but I like to think the confusion was intended for challenge, if it was a simple x-y coordinate conversion it would be way too trivial so I actually kinda like that there's weird unpredictable inertia (even if I'm guessing it wasn't intended that way)
Visual communication isn't perfect as you mentioned below and could help a lot in that regard, but I think the attempt to make a gameplay loop related to audio engineering concepts in general is so risky for a massively non-musician audience that I have to respect it - one thing that maybe could've helped is making the spinning slower? It looks very jittery even in the windows build, but I imagine the speed is related to the actual frequency sooo yea idk, something to think about
The fact that there's multiple different ways to see the frequency as you change it is also a risky move because it can clutter the screen a lot and it can be tough to quickly intuit where to go and what to do, but it makes thematic sense (it's supposed to be a really complicated control panel only Alanteria knows how to work with after all)
On my initial playthrough I only looked at the target frequency and tried to precisely match it, it took a bit of time but it was while I was still figuring everything out, and then the second time through I could speedrun the levels by looking at the circles position for big differences and the error value for small differences. Everything eventually had a purpose, which is really cool, but it did require me to play the game through twice. Maybe you could add some incentive to speedrun a couple levels, if you ever wanted to continue working on it? or some other way to incentivise looking at different parts of the screen, I think the game feels best when you try not to be precise and just do it by feeling, which I never tried to do when I finished the game the first time around (and that first time around was a tiiiny bit boring)
And story-wise I love how grand and overblown it is, but again, it's a weird balance to strike between thematic fluff and clear gameplay directives, the lore exposition between every chapter is very in your face and it's a little scary at first because it feels like you're required to read everything to play the game, when actually no not really, in my mind it could've been a dedicated side panel that you can choose to open to learn more, or something like that
Anyway, great game, could easily be expanded upon especially if you introduce other audio engineering related concepts, it's an absolute gold mine if you decide to go in that direction, but I digress
this was a very rambly comment but I really liked your game, nice work