Well, through many threads in the old Glorantha digests, BRP forums and eslewhere folk discussed the various interpretations of Yelmalio/Elmal/Tharkantus/Many-Suns, trying to descern the truth of what was going on. Funnily ironic given the cults association with the truth rune. I think the idea of Yelmalian Mysticism wad born on those threads and carried forth. Better scholars from different factions of the debate can explain it better than I can.I particularly bow to Simon in this case. Hopefully he can step in.
Going back and looking at the riddling traditions between Orlanth and Yelmalio, it's a tradition that would increase the likelihood of illumination in those cults leaders. Such illumination would allow leaders to ignore cult strictures and lead thier congregations on new paths. So we end up with different cult versions in different areas, slightly altered myths and cult. Simon explores this idea a bit on the Soltakss website. He has lots of great ideas. I steal them liberally for my home games.
Part of the reason for this variation in Elmal/Yelmalio is theoretically the interference of God Learners using their RuneQuest sight, playing with Sun myths in various cultures to unite, or divide, or play as they want, perhaps a possible fracturing of myths as avredult of thier interference. Who can truly know other then a truth cultist steeped in the history and myths of the various cults?
The idea that the 'historical' mythical truth is somewhat variable, especially for a truth cult, might seem heretical, but in a mystic variant of the cult is rather central to the workings of the inner secrets of the cult. Illuminated cult leaders who have managed to avoid Gbajis trap of insanity and doubt understand the Nysaloric truth that they are the masters of their own meaning, their own values, and what the hope to create in the world, both temporally and mythically. It is difficult to explain to those who have not yet been illuminated, but you may get the drift.
While Illuminated Olranthi Wind Lords are somewhat tied to the strong and widespread myths of Orlanth, and have trouble shaking them off, the leaders of these fractured Elmal/Yelmalio/Tharkanrus/Many-suns cults can take/make are more interesting path more easily, particularly using Truth powers under Illumination. Effectively an illuminated use of the Truth rune is to make truth in the world, given the will to manifest it. Thus Balazar made his kingdom, writing his own truth.
This may all sound like utter bullshit to the uninitiated, and to the unilluminated that will always be the case, but once the truth of Tharkantus is laid out before the truly faithful it is plain to see. It is likely the closest thing to the RuneQuest sight spoken off in the old temple documents.
Now, young disciple, what is for breakfast?