To malparaphrase: to describe some event or concept with an inaccurate summation. Malice is not necessarily indicated; it can also be a noun, or turned into other parts of speech appropriately.
Googling it comes up with only 12 matches, and none of them look appropriate (other languages, or things like opti- mal paraphrase, or others with a space), so I can't find anyone else having used it before. Since languages are one of humanity's first open source projects, go forth and use it as you will.