My total note count for all levels is 325, But I don't have the achievement for placing 250 notes. What's the deal?

Sometimes, the core sound mechanics don't seem to work as the user would expect.

I seem to have a problem with the pointer moving slower ingame. This causes levels to become really hard. Has anyone else experienced any problems with this?

It's just playing notes pretty much as if I said C D E F G A C, each and every time going by the exact same sequence. I imagined random but cool melodies kinda like http://tones.wolfram.com/generate/ This site And I was greatly disappointed. Though I played only the first two levels which were... "melodically" identical. Does it ever change?...

I was going fine until I reached Spinel. Then, I tried beating this stage for 1h30m, but was unable to. Is there any strategy to it or is it all about mouse speed?