I want to do that if I ever find the time. Adding a date to the database entries, and some code to throw an old word in here and there based on spaced repetition best practices.

Using speech to text you could say the answer and it could validate your answer. If AI engine is powerful enough it could have you say the foreign word and rate your pronunciation.

As for spaced repetition I developed an alternative which just has a column for number of times correct answer was given and order by descending order on that field. This gives you new words first followed by words you've barely gotten correct etc

> build an anki like system

...or use Anki? Set a calendar reminder to open the app, then there's a similar notification area trigger as with emails

Too much friction, it ruins the email system he made.