The status of "Imperator", IIRC, was confered on a leader by the acclamation of the rank and file of the military. It essentially translated to, "qualified to lead Roman soldiers in battle."
But who* is to say what words were, over the centuries, repurposed to mean something new? The word itself sounds like it would mean, "someone who issues commands" and that fits fine. You can always 'lampshade' it with an explanation of what the term means in this time and place.
* Our beloved writer! of course.