Unfortunately, the answers you are looking for explicitly not public knowledge. Although you can find descriptions of the Age of Lost Omens here (https://pathfinderwiki.com/wiki/Age_of_Lost_Omens$ for example, the whys and what happens are closely guarded by a small subset of the Paizo staff. It is discussed frequently during their mysteries of Golarion seasons at Paizo con, which you can listen to via the know directions podcast if you are interested. Ultimately, while there may be secret canon answers, they have deliberately left them undefined in print to maintain an air of mystery in the setting, to serve as a continual plot hook, and to allow groups and gms to make their own stories.
