Athel Loren wasn't inhabited at all by elves until after the end of the war with the dwarves. The elves instead imprisoned the forest spirits, so if anything considered it enemy territory.
It was only four hundred years after the end of the war that the elves cut a deal with the forest and became the Asrai. That was the point that they lived anywhere beyond the edges of the forest.
There is apparently currently a nexus within Athel Loren.
Karak Norn has apparently redirected its Waystone output to avoid sending energy to the Athel Loren nexus.
Now, some thoughts.
During the Golden Age, the elves apparently feared Athel Loren and its spirits enough that they didn't enter it. In light of that, it seems very unlikely that they would have built a Waystone nexus inside there.
Given Athel Loren was hostile to the elves (and admittedly, anyone else who entered) during the war, if there was a nexus there then then Karak Norn wouldn't have such a strong reason to cut the power supply there, as it wouldn't hurt the elves and might annoy the tree spirits and cause them to retaliate at a bad time.
If there is indeed a nexus inside Athel Loren, is it possible that it was built after the elven colonists became the Asrai? If so, could that mean that Karak Norn redirected the energy flow after then?
That would mean that the Asrai could be expected to retain significant knowledge of the Waystone network. It would also mean that Karak Norn might also know more than we would expect, given they would have had to do so several centuries after the end of the Golden Age.