Amazing job, I'll become soon one of your paying customers :)

After playing with it for a while a first suggestion. I noticed that it's possible to export the frequency of the words so you have this information, for my use case it would be very useful to have this information in the word list (when the word is expanded).

This is because when I'm reviewing the words in my word list and deleting those I feel are not very usual so I can concentrate on those that are, however this is done just by guesswork as I don't really know which words are more common, having easy access to the frequency of the word in the word list would allow me to do it in a more efficient way.