Hello,
I’d like to suggest to add the option to show the on’yomi in katakana instead of hiragana, to match with how it is presented within the dictionaries.
I’m aware there is an userscript for it, however I use wanikani mostly on my phone / with jakeipuu so it’s not an option for me… 
FWIW, that’s an option available on Tsurukame, an app for iOS (not sure about Android).
sadly I have an Android Phone 
FlamingDurtles on android might have it
I’ve been thinking this for awhile. I also wish that the “kanji readings” were consistently the on’yomi readings (sometimes it’s the kun’yomi but the reasoning for when that choice is made is… unclear), but I’d settle for just writing them in katakana to let me know that.
Flaming Durtles does have it.
Settings → Other Settings → At the bottom is an option for katakana on yomi.
I also just recommend Flaming Durtles in general to op, since you can do offline reviews. Not to mention Jakeipuu is no longer supported
Hm, sadly FD doesn’t work for me for some reason. Whenever I try to save the API Token with the permissions asked it just restarts to the same page without the token 
Don’t be sad for being correct.
Maybe ask for help in the FD thread, you really want to use this app. It’s absolutely awesome.