Yes. My co-designer did mention that this is what comes through the least. The module is already so packed that this is one of the things that is not fleshed out and left a bit between the lines.
Let me explain the ancient myth inspiration:
Certain Nahua cultures and Aztec peoples had the creation myth of the five suns. They believe that the world has gone through five distinct cycles of creation and destruction. This is also what I think the mainline solarians believe as they are called The Church of the Fifth Sun. The Sol Incarnate (this Solarian Schism) on the other hand is the Church of the Sixth Sun believing that the previous world has ended and this is the new world. A world which will also end either through destruction (sunslayer) or through the natural course of the binary sun where one sun is consuming the other, and out of this they will be born anew.
That is what the cryptic Solarian prayer in the module is about:
When the Unconquered Sun is consumed by its twin, and the sky forgets its name, the faithful shall be the only light. They shall carry the sun in their flesh. And when the consummation ends, they alone shall remain — and from them the world shall be seeded anew.