I picked up on this too. The demon isn't trolling because it definitely draws the distinction between the time of Arlathan when the eluvians were created and the time when they were last used, during the fall of the Dales. So if this isn't a mistake on the part of the author, there is something odd in this. Who was controlling them at that time? Why was the knowledge lost? In fact how come a demon knows how to activate them when the elves don't?
Even stranger is the fact that in Witch Hunt Morrigan steals a book from a Dalish clan that apparently has sufficient information in it that she is able to activate an eluvian. They were meant to have had it from the time of Arlathan. So why the heck haven't they used it? Or shared that information with other clans? The Sabrae clan certainly seemed in total ignorance, not even fully understanding what the eluvian they found was meant to do.
IMHO there's something fishy about the Eluvian.
It's such a great tool in theory , I mean how can the elves lost so much about their culture when they had the perfect storage place?
Also I agree about the ancient elves , I mean it's the perfect storage and perfect escape plan...so what happened?
And why something in the fade wants the network anyway?
Also yep possible the whole Fen Harel things is related to something the elves did.
My memory is somewhat bad when it comes to details but I think we have :
The elves worshipping their best somniari , building great tombs for them and asking them for advice etc..
Felassan not giving a damn about Dalish and Dalish gods.He talks a lot about the dread wolf but doesn't seem to worship them.
The Fall of Arlathan , the story is the dread wolf locked up the "gods" , they went silent and things went sour .
My brain melts a little because in WOT it says the elves believes Fen harel trapped the gods in the Golden City.
And he patrols the Fade , eating souls or something...
Anyway in the Masked Empire it seems most of the network resolve around important Somniari resting places.Those elves didn't really needed the Eluvian as a network unless they wanted to have their sleeping bodies hidden and hard to reach.
Possible it was a very controlled tool , and only an elite and their servant could use them , and I assume only an handful of elves knew how to activate them.
About Imshael knowing so much , well Felassan was so "Yop buddy , how you're doing?" ...the ancient elves probably worked with spirits and demons at one point.