I've contemplated running P-Harn (personal Harn) that ignores canon somewhat. However, I came up with essentially the same breakdown that you did:
Religion: Theism, with each of the ten gods of Harn having at least one cult.
Shek'Pvar: Sorcery, with one grimoire of common spells, grimoires around the six P'varist elements, and an advanced grimoire for Gray Mages.
You could discard Folk Magic and Mysticism, or keep them as rare forms of magic that the Guild of Arcane Lore either studies or pretends doesn't exist. Folk Magic might work as an alternative or supplemental shamanic/druidic magic, while Mysticism could be a hidden tradition (as in my P-Harn).
Harn also has Psionics, which I'm not sure how to model. Maybe some form of innate Sorcery? An extended version of Mysticism? A simplified port of the HarnMaster system? I like the idea of psionics, but it's hard to wedge into RuneQuest unless every power is a distinct skill, which would means psionicists had to split their experience between mundane skills and their psionic talents.
"Don't get into a spaceship with a madman. Didn't anyone ever teach you that?" -- The Doctor, "Journey to the Center of the TARDIS"