[DiogenesKynikos]

One of your criticisms of spaced repetition is the difficulty of representing associations between words on flashcards. I agree that that's difficult (though you can mitigate it by including example sentences in your deck). However, I think that that criticism expects too much of spaced repetition. It's a very powerful technique for learning and holding onto new vocabulary, but it doesn't replace reading, listening and speaking. You really can't learn nuances of word meaning with flashcards alone, but you can build up and retain a large vocabulary. You can deepen your understanding of the subtleties of the language in other ways.