The Key works, albeit unreliably, without Azem's crystal and has done so at least twice before (and up to as many as five times, depending on how much you want to read into Queen Eternal's "worlds beyond"). Having said that, Preservation (Calyx) was evidently able to figure out how to make it work more reliably, or otherwise had inside knowledge on the thing that the Key's original Milallan handlers did not.

Besides which the Key's interdimensional bridging is nothing like Azem's magick. On the other hand it's essentially a massively upscaled variation on Halmarut's ability to punch holes in the dimensions, suggesting (to me) it may be more closely related to her than Azem. Even then though, we have no clear information on how the Lalafell / Milalla got it to work in the first place, let alone where it came from and if anyone else got it to work beforehand. Perhaps it responds only to a need and not a desire, or the dimensional bridging is only part of it's capabilities (that is to say, it could be a wish-granting device with limited capabilities). The fact the Ascians never bothered to scoop it up and exploit it tells us either they didn't know about it, didn't know how to make it function, or didn't think it worth the effort, and only the last of those raises fewer questions than it answers.

Regardless, according to Miyali the Key chooses its owner, not the other way around; while that sort of mysticism is rarely attached to nonsentient artifacts, if anyone would know it would be the descendants of Aloalo's Speaker.

All of which is to say we still have virtually no information on the Key other than "It can make bridges between the Source and reflections, sometimes," so "Azem created it for their future incarnation 12,000+ years ago to resolve the post-Endsinger crisis showing up now, which they knew about because of precognition; their symbol showing up when the Key was invoked proves it" is seriously jumping the gun.


And the fact Enuo has apparently been cast as a Voidsent lord means we still don't know where the plot is going, other than Halmarut's ominous "If you try to save [all of] the reflections, everything will be annihilated" Big Doomer Energy speech (which we still don't have the full context for, either).