To be more precise, the Ultimania says she's "Xion from when she first joined the Organization", which makes no sense because she didn't gain a Keyblade till after she formed an identity (which is what caused her to continually go rouge). Before that she was confined to basic magical spells, so that already contradicts what we see in the game.
Not to mention how useless such an idea is to begin with. What exactly separates that version of Xion (who's bassically a drone) from any other replica? Why not just make a new replica from scratch? Going through all the effort of bringing Xion back specifically is functionally pointless. Especially when no one in present time even remembered her as far as they knew.
Also, what was the point of the Org's experiments if they were really meant to bring Xion back? First of all, plucking her heart from the past doesn't require anything other time travel and a vessel, and that's not the same thing as "recreating a heart" in any way. Why would they need a "clue" about how to "restore" Xion, if all they're doing is the exact same thing they used to pull Ansem SoD, Xemnas, and Repliku into the future? There's nothing to figure out that they don't already know (unless the writers had two separate explanations for Xion's return, which is what I'm guessing is the case).