I think the problem might have to do with not being a native English speaker (at least in my case it does). I very frequently know what word is supposed to mean but can not think of the correct English term or I get it wrong slightly because there is some nuance in English that makes a difference and that I‘m not aware of. Adding tons of synonyms is not a viable solution for me either so I love the Anki mode. But of course also, typing on mobile is just painful.
I feel that being able to do reviews in a less painful way makes it more likely that I keep up with them which is the most important thing. Also, even if it is slightly worse for memorization (which I don’t doubt) I don’t think it is that bad since a lof of people are using Anki successfully without typing in answers.
To solve this, I made my own build of the Allicrab app. I don’t know if the creator of that app is open to adding it but I would happily contribute some scripts to it so that others can use them too. This is the thread about that app: https://community.wanikani.com/t/ios-mobile-allicrab-for-wanikani
Scripts that I tested in the app: [iOS] Mobile AlliCrab for WaniKani - #351 by irrelephant