The Grand Cosmos was not a part of Voeburt at all but instead Lakeland and the civilization of elves there. Voeburites are drahn and galdjent. Lakeland is elves. The only connection it has to Il Mheg is that a nu mou mage moved in after everyone who lived there died. The shades are probably recreated by them to remember the splendor of the old days before the Flood.

We probably won't learn of any connection of warg gear to the dungeon, if there even is one, until a 3rd encyclopedia comes out.