When I come across a word/kanji/radical that’s really hard for me to remember at first, I come up with a better mnemonic for me and stick it in the notes section. Sometimes I think my mnemonic might help other people, but there’s not an easy way to share it.
What if there was a button near the note I made that allowed me to share with others? Maybe you could opt in to seeing other custom suggestions and vote them up or down. Or, the suggestion could go directly to someone at WaniKani to review and see if it should supplant the existing one.
It seems easier to integrate this into the website than posting each suggestion on the community. If the button was on the website, I would be MUCH more likely to contribute.