So if we think about the transmission of Solar myths into the Monomyth we get something like:
Dawn Age: Orlanthi and Dara Happans recognised each other’s myths and placed them in each other’s collection of stories.
Late First Age: Arkat fits Orlanthi and Darkness myths into a Malkioni framework. These included mirrors of Solar myths (and bits of the Orlanthi-Solar synthesis above).
Second Age: God Learners get everything they can out of the conquest of Arkat’s Dark Empire and loot all of the above. They go on and conquer the Solar Teshnites, identifying Yelm with Somash, Dayzatar with Zitro Argon, Solf with Lodril and so on. They also conquer Kralorela and identify those ancestral emperors with Solar figures. Not only that, but at Feroda and Robcradle they gain direct access to the Pure Horse People and get that deep Solar mythology – which they fit back into that system.
Meanwhile the Orlanthi continue to integrate Solar myths into their framework – Yelmalio, Dara Happa, and Pure Horse People.
Now in Dara Happa, there is no doubt greater access to Orlanthi myths, but with I sometimes think that the Yelmites and Dayzatar priests are content with looking at the Gods Wall and concluding these are all rebel barbarians and dragons who have turned the world upside down, and sooner or later the proper order will reassert itself.
Third Age: Orlanthi heartland is destroyed. Dara Happa is placed under materialist rule, and the Solar myths are fit into a Carmanian Malkioni structure with many Darkness stories hanging off that framework as well. They aren’t God Learners but are synthesisers despite hating the God Learners.
A group of rebels against the Carmanians do a deep dive into the backwaters of their stories. They assemble bits of largely ignored Solar stories that didn’t fit into any structure, added some Darkness and Orlanthi elements to it and tried to resurrect a dead goddess. Who knows what they were hoping for – maybe Sedenya, a largely forgotten cyclical goddess associated with the Blue Moon, and who knows what they expected to get out of it? But they succeeded beyond their wildest dreams with the Red Goddess, who then reached down deep into other stories even the God Learners feared to investigate and came back with a mastery over the demons of Chaos.
Meanwhile the Orlanthi reclaim their heartlands and rebuild with plenty of assistance from God Learner influenced scholars and a curious and adventurous dynasty that promotes roads and libraries and reclaims old Second Age sites. They put Yelmalio firmly in their stories, emphasise several deities known to both the Orlanthi and Solars, but also give the Trickster a prime place.

See also
In this way, stories and myths have been transmitted across Glorantha and fitted into mythological frameworks.
The Lhankor Mhy grabbed god learner insights and ran with it. Did the Buserian cultists do the same in DaraHappa? Same god, same cult, different names.