Whew. Alot of cataclysmic events listed here, to be sure...
My game is based moreso on FIXING the fallout from the cataclysmic events of 150 years ago, not creating more (at this time, anyways).
I think alot can be achieved, more along the lines of serious intrigue, by having the golem move ever so slightly. Perhaps it's head turns ...???
Say it's head does turn, and faces (picks random direction) east. Is it a sign? A foretelling? WHO made it move. Why did it move. What's going on in the east. East can easily be all the way to Darakeene....Not very far for a divine entity...
Is the golem looking east, so as to NOT look down on Mithril due to some displeasure? IS the PP behind this? Or some other faction. OR is Corean sending a message?
As you can imagine, you can have alot of the same shakeup in faith, as if you had the golem walk out of town, without the destruction, and resurrection of a titan.
The intrigue in this scenario can a long turn into research, investigation, possible planar travel, and can lead into a huge campaign...
While the PC's are one of the key groups looking ino the golem moving his head, the status quo in Mithril, and the priesthood, still can factionalize, with all involved steeling themselves for what could be an epic event. Some are positive, saying it's a divine signal, others are the doomsayers, where the head turning is foretelling of doom. Then, there are all those in between...
The unrest could easily trickle to the PP, and other factions seeking to usurp Mithril in any way possible, who optimize on the unrest. The PP moves in and begins to feed the fears of the populace, sponsoring various unrulies and pirate bands to run amok in the city.
I know it's inevitable for a titan to 'come back' eventually. But, a big epic event need not have epic events to fuel them, IMO.
Just giving a different line of possibilities.