When it comes to “Jane”, I think what will be most telling is if it reappears in the code for something else aside from Joker.
For example, if in the next update “Brave” and “Jane” are there, we’ll know it was meant for something else. As of now there really is no way to figure out what it would mean without more information.
Considering the new Persona girl has a ponytail, and the “Jane” file was with Joker, it could still have a connection. Based on what folks have been saying , it could be late but scrapped data related to a Joker costume.
With that in mind, who knows? I wouldn’t rule out the possibility that because it was scrapped late, it could...maybe, become an echo fighter later.
But I wouldn’t expect that. Just view it as a distant possibility.