It depends on the edition; Russobit initially released it, and then Akella did. Russobit's version calls it a Satyr, while Akella's calls it an Imp. I personally prefer Russobit's translation because it's more literary and not a mindless translation based on a prompt, like Akella's, but I still get confused sometimes.
Well, I don't know; I have Akella's licensed version, and the translation is at a good literary level, not a literal translation. However, for this unit, I think both Imp and Satyr are equally bad names (although I'm more used to Imp).
