Greasy Fork is available in English.
Allows retyping typo'd answers, or marking wrong when WK's typo tolerance is too lax.
< Spätná väzba na Wanikani Double-Check
Sorry so long in responding to this. For some reason, GreasyFork isn't notifying be of feedback, even though I have the appropriate settings checked in my preferences. There's a new version that I think fixes your issue.
Update 2.1.0 seems to have broken the 'esc' or 'backspace' functionality which allowed you to retype your answer after a typo.
Breaking after on-yomi error
When you write an on yomi on a kun yomi or viceversa, you get this popup reminder of your error from WK, staying in the same item, and waiting for you to try again. But when you do it wrong again, it continues, showing the error, but going to the next item. This is due to this script.