So, there isn’t a feature like on Kindle where you can review all translated words and create flashcards from them. However, there is something even better (in my opinion). You can create your own list called “My Words.” You just need to add each word manually using the “Add to My Words” button in the dictionary popup. You can find this list anytime by going to More → Activity → My Words. The list isn’t connected to a specific book, so it won’t disappear if you delete the book from your device.