I mean that he might be the intermittent one instead of Quirrell. If maps like these really do show one’s true name, as with Scabbers and Crouch in Canon, then Quirrell probably knows about them and made himself generally unplottable, not just intermittently.
I think it’s likely that Harry is one of those errors. We he goes dark-side his name might change.
I don’t think George would describe a glitch where someone’s name changes as being “same as ever”.
I mean that he might be the intermittent one instead of Quirrell. If maps like these really do show one’s true name, as with Scabbers and Crouch in Canon, then Quirrell probably knows about them and made himself generally unplottable, not just intermittently.