Yes, or the one I prefer: [Userscript] WaniKani Wrong Answer Delay. (There are a few similar scripts and I tested a few, but I forget why I preferred this one.)
As to why one would use the override script, I’d add that many of the standard WK definitions especially for kanji are quite narrow. So if you know what an item really means, but the word you typed doesn’t match the WK definition, then I think you’re justified in using the override script and adding your own synonym.