How did you use a memory palace to memorize 2,000 kanji and Japanese. I thought memory palaces were only good for remembering things in sequence, but I don't see how that fits with language or kanji.
As for vocab, for example I would go for a walk in the park and create memorable mnemonics for the vocab words I saw and the park itself would be a memory palace. Later when I wanted to say the word "vending machine" I would pull the Heisig mnemonics for the vending machine I saw in the park and recreate the word. Today when I'm speaking Japanese I don't have to think about about mnemonics unless I've forgotten a word, then I kind of "look it up" in my memory palace.
The thing about the memory palace method is that it's not really fast recall, it's more like keeping a notebook in your brain until it has been adjusted to your working memory.