The whole point of Resonance is that it's a "copied" Echo though. A replica made without access to whatever created the original.
And Arenvald definitely mentions Hydaelyn, or rather what must have been a similar vision of Her to what we had early in the game.
Right from the beginning when we first meet him at the Waking Sands:
I had a dream unlike any other. I was myself, but then I became something...more. When I spoke of it to others, they directed me here. Did you have one too?He may talk more about it later too, but that's the one I definitely remember.They say that those of us who have seen the dream are chosen, that we have within us the seed of greatness. That we could be heroes.
Even me, an Ala Mhigan half-breed, cast out when his mother could no longer stand the sight of him. A half-breed who once took to banditry just to eat. Aye, I'm sure I'm just brimming with heroic potential...