It’s not exactly what you were asking for, but maybe someone would be interested in my review audio tweak script.
https://greasyfork.org/en/scripts/10184-wanikani-review-audio-tweak
allow audio to be played after review meaning questions, when reading has been previously answered correctly.
also includes enable autoplay when incorrect setting (default: off). this was requested by someone?
also includes enable autoplay when incorrect setting (default: off). this was requested by someone?