Hey there Yveline, welcome to WindWorks and thanks for your post.

The answer to the chromatic is to slow it right down.

Some people like the idea of really hammering the fingers down.

Another suggestion is swapping hands and developing it with your left hand fingers; this uses a different part of the brain and when you swap back it seems easier.

As far as the charts go, have a read through this thread: https://mysterytomastery.com/topic/progress-chart-labels-a-tad-confusing/

Cheers,
Greg