Thank you so much for the detailed feedback! Glad you enjoyed it.
I'm glad you pointed those two things out, as they were actually things we were aware of and unsure about as well, haha!
We iterated many designs for the direction buttons and landed on this one as it had theleast visual clutter. But after implementing I kept saying that its too hard to tell them apart. But we didn't really have the time to change it anymore.
And the note sounds is also something we changed 2 or 3 times. I had the same feeling that some combinations felt too dissonant. We tested having the 4 notes be the same but in different octaves or have them be the single parts of a chord, but that also somehow didn't feel quite right either. I think it would have taken a bit more testing of different combinations.
So at least we didn't imagine it haha!