I've been working on learning spanish for a while and this looks super helpful - thanks for creating and sharing it! It would also be sweet if you could add an example of the verb used in a sentence after you've submitted your answer/guess, and then maybe a button to see that example sentence translated back to english. That would be a lot, but just a thought.
I hope to add audio, more tenses and more feedback (on your progress through each round) soon.
I wrote a blog post on the development here for anyone interested: https://andycloke.github.io/Building-Verb-Master/
This was my CS50 final project. Can't recommend the course highly enough.