The word “mondegreen” appears neither in Benson, nor in Wells, nor in Vikivortaro, nor in ReVo. How would you render it in Esperanto?
Mondegreen - a misunderstood or misinterpreted word or phrase resulting from a mishearing of the lyrics of a song. - Google
Misaŭdaĵo = a thing that is misheard
In my native language, Danish, there is no one word for it either, and native speakers just call it “misforståede sangtekster” which translates to “misunderstood song lyrics”. Thus I'd just translate it to “miskomprenitaj kantotekstoj”.
There's no reason to overcomplicate a translation by inventing a new word. When translating, the goal is to translate the meaning, not the words.
misvortigaĵo comes to mind: that the words were constructed wrong. Not very convincing. I like fuŝaŭdo, which seems better than mis~.