vocabulary overview feature?
I think it would be very convenient to have a quick way of seeing how many of the words you have in your studies you know how well. (even just showing the respective percentages for the four bars)
Maybe even with a warning that if, I don't know, maybe 50% of your words only have one bar, you should do some vocabulary revision instead of new lessons.
At the beginning, the vocabulary section as it is now might be enough, but I have about 800 words in Spanish right now and it's not helpful.
What do you guys think?