As you can see, the original font on the left displays wrong radicals, for example, Ashes 灰 incorrectly shows By one’s side radical, which is all fixed by this method.
Works great with other Styles, for example Dark Memrise (it will activate both effects of corrected fonts and alternative color scheme).
Thank you, Tonbo, for answering my question and confirming that the userstyles tweak would fix my problem. I was already considering that as a solution, having earlier read the topic that Hydroptere linked above. And thank you for your reply and link, too, Hydroptere. However, the problem in that link referred exclusively to kana, so wasn’t sure if the fix would the same for kanji.
In addition, I wanted to bring this problem to the attention of the Memrise PTB and the course creators, because I assumed that they would want to correct the errors. Most people taking these courses aren’t going to know an incorrect kanji when they see one; they’re just going to learn the wrong thing. And if Memrise isn’t going to do a fix, maybe the course creators could at least put a link to userstyles in the course headers.