So, this is actually a deal-breaker for me, and I won’t be using Wanikani anymore.
I know the typical response on this forum to such statements is “Don’t let the door hit your ass on the way out,” but after a year, off and on, of trying to make this program work for me and running up continuously against the need to spend excess time learning meta-knowledge (knowledge specific to Wanikani and not Japanese as such), of which this is only the latest example, I think it is only kind to let the devs know why I am leaving.
I wish the devs lots of luck! I hope you can continue improving this site and implementing additional flexibility so it can meet the needs of a wider variety of learner types.
I also wish my fellow Japanese learners lots of luck and success, and thank you to everyone in this thread who linked to various solutions and workarounds. It wasn’t enough to meet my particular needs, but not for want of trying, and I am grateful for your attempt.