The split between on’yomi/kun’yomi on Wanikani’s kanji reviews is something like ~1700 on’yomi, ~300 kun’yomi. The idea is that you hopefully learn whichever reading is more useful to know when you see the kanji in an unfamiliar word.
I’d recommend using [Userscript] WaniKani Katakana Madness, because with it, you’ll passively learn whether each kanji reading is on/kun based on whether your answer appears as ひらがな or カタカナ. You’ll also get more exposure to katakana, making it easier to read at a glance
I’ll give my thanks as well. I must’ve missed this script when I browsed the script list previously.
Still, with any previous kanji knowledge, it is fairly frustrating to go through lessons and reviews by trying to first input on’yomi and have the system ask you to try again . (There should be a more clear visual clue as to what is asked…)
On this level 8 alone, there are five kanji that teach the kun-yomi and many times I doubt the WK reasoning of choosing the kun’yomi. I kinda get 雲, as it is a standalone word. But for kanjis tied to verbs like 買, I can’t see a logic to learn is as か , since you’ll never see it as a standalone か and 買う kan be taught as vocab soon enough… Also the reading ばい is not rare at all… (sorry, this turned to a rant)