I have these two storyline/epic quests, but I can't find any info on them. We did the instance and fought the Scout Commander, but never saw the other two groups and never did find the den of Naveer the Primal?
There should be 3 groups which spawn for the Coup. A group spawns after killing each of the first three bosses: Spring, Summer, and Autumn. I am assuming that this didn't happen for you but couldn't say why. The quest acted buggy as **** when we did it too, so I can't say I'm surprised.
No idea on the other one, haven't done it yet.
One day on Hib/Guin, the Hibernians finally defeated the Dragon and the Gods were so startled they caused the sun itself to go Supernova.