Sorry for the late reply, but thanks very much for the feedback! Yes, doing the same for other languages is something I’ve thought of too. If I knew German, for example, that’d be great fun (thinking of using works by Goethe and Nietzsche). For now, this is a one-man show so I’ll have to keep my focus on just Japanese.

> How do you envisage the fluency colour coding being used?

The color-coding is just to visualize your progress if you are recording how well you know words. Red indicates words you don’t know or haven’t recorded anything for. Each time you click “Got It” for a word, the color will be updated to a new color: red -> brown -> yellow -> light green -> green (green indicates you know it completely; clicking “Know It” will make it green immediately).