Part of the way the WaniKani system works is that you also need to prove to WaniKani that you know the Japanese. Yeah, spelling can be hard sometimes, but unfortunately WaniKani needs to be certain that you understand the meaning. Sure, it can let typos through if they’re close enough, but if that typo also happens to be the correct answer to a different item with a different meaning, it needs to say “no, not close enough”. For example, “north” is close enough to “south” to be accepted as a typo, except they’re antonyms.
Perhaps you want to try installing the Double-Check script. It allows to mark any incorrect answer as being correct. But be careful - with great power comes great responsibility. If you just mark every incorrect answer as correct while thinking “oh yeah, I knew that”, then you may as well be using Anki.
We had a guy here a few years ago who was complaining that WaniKani didn’t let him add enough synonyms - he’d added synonyms for spellings of 入院 that ranged from “hsptlztn” to “hposaopijtiln”, and we had to sit him down and point out that perhaps WaniKani isn’t for him…