I see a lot of requests of adding new languages. How about we just have an option to upload a text file with our own custom dictionary of words we need to learn and translations of these words to the languages that we use in everyday surfing?
This gives 2 things:
  1. People can add their own languages and even share dictionaries
  2. People can only learn the words they need by limiting the dictionary, adjusting it however is needed for the best learning experience.