I like the use of the coloured squibs giving the tone - but I'd go further. Don't bother changing the squibs to black as they become strokes, leave them in the tone colour. And, you can likely do away with using the colouring to mark the grading level. Colour is more useful for tones than it is for grading.

Hmm, yes. I will try it later. I'll try either getting rid of the glow or making it grey or something, for writing prompts that will use the coloring.