Yeah. I refer to the red walls on Level 5. I call them "inverse" walls due to how they invert the controls. It's weird because I expect the controls to go back to normal when I come across my first normal wall, and not the last "inverse" wall. Again, I guess this is something I'll have to get used to.
The pattern spacing I notice is something throughout the whole game. It's not too big of a deal on the first level, but when speed picks up it starts to become a much bigger deal. I think the wall thickness is fine for spiral patterns. Just for barrages, I think the walls could half their thickness and it'd be perfect. Same spacing and it'll be good! :)
What happens for the music glitch is that whenever you leave the application out of focus for too long, the music doesn't loop and stops completely, and this prevents any additional music from playing until you leave the level.
I see what you mean with the red walls. I think I'll add an option so that people can play with the mode you describe instead if they want.
Walls feeling too thick is not something I've noticed myself or heard from other people who have played the game a lot. But the way you write about it sounds convincing. I'll experiment with reducing them and maybe make some alternate thin-wall versions of levels for people to try in the next update.
And thanks for identifying what causes the music bug, that's very helpful. Will fix.