I doubt that it'd be too difficult for the lore team to justify. The full capabilities of Magitek has only loosely been touched upon, anyway - and it's very likely that there's significantly more powerful/valuable technology in the inner territories. After all, Regula even goes so far as to conjure a ceruleum familiar. We've also seen a lot of Allagan technology re-purposed by Garlean forces and teleportation seemed to be fairly common back in the glory days of Allag. A lot of it seems to have been left intact, too despite all the years that have passed.