With how the denizens of the deltascape are introduced all they amount to is a casual reference. They have no bearing on Omega's plot which would seem to be wholly original. They don't even really exist being conjured from some story Nero had heard of. Which incidentally suggests some version of FFV would seem to exist on Hydaelyn. Most likely in the form of a book, but possibly in the garlean equivalent of a video game and the idea of Nero playing it on a super Hingacom is hilarious to me.

Back to the subject at hand while XIV uses a lot of stuff from previous games I feel its in a sensibly remixed manner. No Kefka equivalent for the warring triad, the war of the magi is entirely divorced from the triad and given much more development, the crown prince solicits divine help not to end the interference of gods but because hes a total nutbar, etc.