Lathander & Amaunator history: what is the Deliverance?

I am DMing a homebrew campaign and I am developing a subplot related to the cleric’s background. This subplot involves the gods Lathander and Amaunator, I am mainly interested in the Dawn Cataclism and in how Lathander acts to the greater good without considering the consequences (as written in Faith and Pantheons, 3rd Ed., pag 37).

I have read some materials and answers about the past of the two gods (Three-Faced Sun heresy, Risen Sun heresy, Post-Spellplague Era and Post-Second Sundering): but I found nowhere any info about the Deliverance, mentioned again in Faith and Pantheons (pag 38) and in the Forgotten Realms Wiki page of Amaunator. I searched also on the Sword Coast Adventurers’ Guide but there is scarce information about the Faerun pantheon.

My thought is that the Deliverance is some sort of omen that anticipated the facts of the Post-Spellplague Era, but I would like to have confirmation of it. Does anyone have updates or information about it?