By the way, for anyone curious - I'm pretty sure I figured out the 'trick' to the spawn timers on researchers when they are supposed to spawn during the server resets - it literally just skips a day and spawns at the same time the next day. So, for instance, if the server is down at 10AM PST on Tuesday 25 July and the Priest researcher is due, it would instead spawn at 10 AM PST on Wednesday 26 July. (Which has the unfortunate side effect of making it impossible to make long term schedules for the timers, since the downtimes aren't actually a set schedule, with randomly happening on wednesday or having shorter/longer downtimes)
Updated Celestial list. Still not sure whether all the Challenge mobs can update it or if maybe Nirag is an additional mob for everyone? Need more info.
Brigand in my guild got the first Ancient update (the one supposedly from T2 bosses) off Slither Rattlebones, the T3 at the end of Raj'Dur Plateaus.
I can confirm Dirge, Troubador, Coercer, Illusionist, and Inquisitor Ancient T3 updates as Hambalumi <Mhyt-moo Migmu>. I can also confirm Monk, Guardian, and Paladin Ancient T3 updates as Ragtag the Despoiler.