http://dragonage.wik..._Sentinel_Elves
Admittedly I'm making a bit of an assumption, but here Corypheus seems to imply that he's gotten his elf knoweldge from the Orb.
I dunno. I just don't see the Well of Sorrows as something that Mythal is happy to spread knowledge about. While all of the gods may have had such tools for their priesthood, I don't think they would let that knowledge be put up in a painting in a tomb under the Western Approach, y'know? 
Interesting but yeah, vague. But that makes me wonder how Cory himself knew the orb was elven. But then, Cory was from before the First Blight so there could have still been ancient records. He might have known what the orb was from before since there were ancient images of Dreamers with orbs like that one.
Also interesting from the Calpernia excerpt ... the power of the Sentinel elves was like the power from the orb.