Well, it's just speculation at this point, but here goes...

The Akadaemeia Anyder dungeon, along with some tidbits from Amaurot (the location), directly linked Lahabrea to Phantomology, which in turn was the study that gave way to the creation of Guardian Forces (and later primals). While Fandaniel played an important role in Zodiark's creation, I've no doubt that Lahabrea had an equally important role in that.
Post-Aitiascope/2nd Trial, the Loporrits reveal that the rituals used to summon primals were deliberately modified by the Ascians, such that the summoned primal would be compelled to spread their influence via tempering. While the way this played out depended on the primal, it's suggested that a primal would have to be on the same power scale as Zodiark to temper others just by existing.
Finally, when we encounter Hesperos, his devotion to Lahabrea is warped to the point of fanaticism. Just like the majority of the tempered we've run into. He even kills himself to cover up what's been happening in Pandaemonium, inadvertently implicating Lahabrea because of that loyalty.

With all of this combined, I believe that—by the end of Pandaemonium—we'll learn that Lahabrea is directly responsible for both tempering as a standardized concept and specifically Zodiark tempering the Convocation. But that's a pretty reasonable guess, I'd say. So here's the crazy part: By the end of Pandaemonium, it will be revealed that a chain of events have been set into motion that result in a divergent timeline—one in which appropriate checks are in place to ensure Zodiark can't/won't temper anyone. As a result, the conflict growing between Amaurot's people post-Final Days will not be beyond reconciliation and the Sundering will be averted, giving the Ancients their chance at a brighter future.

It's as much wishful thinking as a crazy theory, really.