It is widely known that most worlds of Old Memory were characterized as spheres floating in “space”, though there are also tales of more exotic locales (such as hollow worlds). Similarly it is widely known that most worlds do not in fact have a sun that is literally a fireball streaking across the sky. The populace is generally aware that the accepted cosmology of Phoenix would be considered fanciful in most other places. Of course, all but the Reborn consider the worlds described in their tales to be likewise fantastic and strange.
The ideas of writing, language, mathematics, art, civilization, technology, etc. are (in many cases) understood to have been imported into Phoenix by the Reborn, and is (in most cases) considered a good thing that this young world was given a head start rather than having to rediscover it all on its own.
Beyond the above, agreement starts breaking down, as the Reborn do in fact come from so many different worlds and times – there are often contradictory “truths” revealed between the testimony of one Reborn and another.
There are also those that believe that Old Memories are a hoax, a myth, perhaps nothing more than vivid dreams…or perhaps nothing less than revelations (or madness) from the Gods.