I see it as some half remembered dream much like some of the murals in the Qitana Ravel. A possible clue to the Final Days. That there was something more going on than just the Hydaelyn/Zodiark feud as remembered by one of the Sundered. Which we know is the case, because instead of actually dealing with the issue themselves, they summoned Zodiark to deal with it. The XIVth left to try to find the source of the problem but ran out of time or was killed by the cause of the sound. For all we know the painter of the murals could have been Hythlodaeus's fractured incarnation (that is wild speculation and not at all backed by any information).
And yes, essentially that would be what I'm saying. Something is buried in Silvertear Falls under the Guardianship of Midgardsormr, and there is a huge reserve of aether there for a reason. As for the Ascians not finding it after all the years that followed, Midgardsormr is still alive and holding true to the covenant he made with Hydaelyn to protect said lake. Meaning they can't deal with him easily and are weary of doing so. So in the Source we have Silvertear and on the First we have The Source where Bismark is currently residing. One is surrounded by crystals and the other has those same crystals growing out of it, and both have a guardian of sorts watching over it. That is not a coincidence. There is something more going on here. I wonder if next patch will have Fandaniel place one of the Towers (Black Omens maybe?) in Mor Dhona, one for every calamity thus far...