Yes, it does, but as I am writing a novel set during the reign of Louis the Pious, I do not want to make the mistake of calling him Charlemagne before it became used. So far, I am referring to him in conversations as Great Charles. I suppose the same problem exists for Germanic Aachen and when Aix la Chapelle came into use. One source I found says the transition to a regional French language emerged in the mid-800s.