Thank you for your review!
I'm currently working on a 1.1 update which will add some quality of life improvements. Being honest I never thought that someone would actually try using the map editor; that's why it feels more like an internal tool than something that's meant to be user-friendly.
But what you might like is that in 1.1, the snap modes will no longer be limited to 2^s, and you'll be able to set it to 1/3, 1/4 and lower.
Additionally, scrolling with W/S/scroll wheel will now respect the current snap mode and BPM instead of the hardcoded 500ms.
I never fully explained all of the editor controls, again I never thought someone would use it, but with 1.1 I'll be sure to include some kind of help section.