Today I finally had enough. First I considered making a user script for WaniKani to make it work a bit more like Anki (where you don't type the answer at all, you simply indicate how well you knew it with one tap). But then I realized that I might as well just use Anki directly.
I quickly found wanikanitoanki.comcache, which is great to export all Radicals, Kanji and Vocabulary and has really nice Anki templates too. Alas, the exported data didn't include the critical mnemonics! Presumably because these aren't returned by WaniKani's API.
Luckily, WaniKani is almost trivial to scrape:
import requests from bs4 import BeautifulSoup s ...