Well, that was an info that's been around for a while waiting to be used, I remember hearing years ago that Xanadu actually learned magic afterwards, which season 4 finally showed, it's possible that was always the plan even, which's somehow even worse to plan her to start as a Charlatan who becomes the real thing, instead of realizing that Xanadu being a charlatan is bad and retconning to fix it lol.
Y'know, reading all of this, they could at least excuse YJ's Xanadu being a charlatan by using this plot point about her losing her magic, and also making her be amnesiac, so at least a "fated encounter" with Kent Nelson could be what makes her recover her magic by actually seeing the real thing.
At least that way there could be a better excuse for her to be a charlatan, and while we'd still have the "She didn't know magic but now she does", it would be slightly more faithful to her comics version at least by description.