That attitude is going to kill what little energy the AF fiction branches story has left.
This is an ongoing story. Yes, it's based on Altered Fates but it's still an ongoing story, and the nature of these stories is to change over time. There's absolutely no reason why anyone has an obligation to fit it into AF canon because it's not going into the canon anyway. Relax, don't stress the rules, and maybe people will actually come back to this story and not keep going back to YAWYW in disgust. If the functions of the medallion change as the story evolves, that's fine. That's part of this sort of game.
It's a game, not a serious story. Neither you nor anyone has the right to hijack threads to reimpose the "rules."