You can add synonyms to items which will also be accepted as answers to work around radicals/kanjis for which you don’t agree with the ones provided by wanikani. Be advised though that the mnemonics are built with the Wanikani meanings in mind.
For small typos/meanings that are nearly identical there is a userscript you can search for in the forum wihch provides you with an undo function. Be VERY careful though to not abuse this functionality because you can easily fool yourself into thinking you know an item even if you don’t. It can defintely help though in the rare cases where it is obviously just wrong by accident. ([Userscript]: Double-Check (Version 2.x) for example there are others too)