Do you guys thing they are one and the same? If you haven't done the black mage questline, she was the original creator of the Stardust Rod relic, as well as one of the greatest black mages (iirc she may have invented it), in the 5th Astral era. Your soul stone is the "Gem of Shatotto".

Shantotto (from FFXI) herself messed with multidimensional magic in the "A Shantotto Ascension" story, so maybe she ended up in Eorzea?

(And yes, I know we will have a FATE with her soon).