The bug is also present in the Kheldian Quest, specifically "Fear and Loathing in Striga." I didn't capture the instant, but it was a named Archon. I think his name was Booker, the first guy you run into during "Investigate weapon test" in Part 1. The instance was level 25 with Adjust Level +0 and the enemy spawned at level 30. Fortunately I was able to teleport past him.
Ran into another instance of an enemy being 5 levels higher than the instance in Part 4 of "Fear and Loathing in Striga" with Archon Stone. I'm pretty certain it's only happening with named Archons.
Happened a third time in Part 5 with Archon Turley. This time I took a picture. It didn't happen with Lt. Wester who is also in this mission so I suspect it's only the named Archons.