I entered Azteca and I still don't know what its talking about, they say that the world was destroyed and everything and they thought everyone in azteca was dead but we find them to see another meteor coming to destroy Azteca. Then Azteca was still alive but to see another comet coming upon it. Is that the same comet that destroyed Azteca a long time ago or is that another meteor. They had 2 apocalypses, one currently now, I never skip dialogue so I can see whats going on but I still don't understand.
From what I can tell, Xibalba is still the same comet that threatened Azteca 10 years ago, but due to some peculiarities of its orbit, it blocked all of the spiral observatories capable of spotting Azteca. This, combined with the coinciding loss of all communications with Azteca, led many to believe that it was destroyed by the comet.
As to the comet moving to allow observation and transport to Azteca, my assumption is that the spell that the mystics cast to summon help did something to either physically move Xibalba just slightly, or do some weird metaphysical stuff.
The destruction you might be confused with, was the shattering of the First World which created the Spiral as we know it today (floating worlds). The Lords of Night (Azteca dinosaurs) were there during that event and heard Bartleby sing the Spiral into existence (Song of Creation).
What I think happened in a simple way, is that the comet is somehow blocking up Azteca- and it's the perfect place an evil lair would be. So, you go there to examine the "hidden world" of Azteca. You find out that "The Shadow Queen" is trying to concur all of the pyramids, and if she does, Azteca will be doomed. So, you're collecting things to make weapons, to cut of blockaida, and more.