What's the point with that quite lackluster story in Endwalker?

[Lauront]

This is only if you go the route of patching up the celestial currents. We've discussed this here before, but among the things we know about calvinball dynamis is that it can't affect aether of a certain density, that's why Meteion couldn't affect the ancients themselves, only their creations and other less dense lifeforms. The correlation with the stagnation of the celestial currents was the only thing they could find in the dark that worked, without knowing the actual cause of the problem.

At the beginning of our visit Hermes commented in the presence of Emet and Hythlodaeus that aether trumps dynamis, that knowledge is already a good starting point in finding solutions if the ancients were even half the scholars and researchers they were depicted as.

And to add to this, it is scholars in the plural (known from the Watcher) who were credited with discovering the celestial current method. Not just Hermes.

[Sicno]

And to add to this, it is scholars in the plural (known from the Watcher) who were credited with discovering the celestial current method. Not just Hermes.

Yeah, and even if that wasn't the case just knowing something "exists" already speeds up research on it tremendously as an uncertain, accidental discovery is no longer required and is replaced by conscious efforts, theorizing and trial and error.

Having other researchers already be initiated in the concept would speed things up even more and it's entirely possible that dynamis research would have gone viral. But no, it was kept a secret as the world fell to ruin.