Thanks for the feedback!
Regarding your specific points:
Gale Winds is really good for stopping fast deathstar units like 12xNecropolis Knights or Stonehorns from getting a turn 1 charge. I was actually worried a 6+ was too low to cast.
Celestial Mending should just be D3/D6 heal. The 6+ ignore was an idea I had but forgot to remove it before publishing.
Drain Magic also reduces enemy casting rolls by 3, which makes it harder to cast and also easier to unbind. In my limited testing I have found that it shuts down casters (which fits perfectly with what a Slann ought to be doing!)
Celestial Rites are like Stormcast or Khorne prayers. Any model with SERAPHON PRIEST can learn an additional prayer before the game begins and "cast" it on a 4+ it in addition to any other prayers they know. Currently the only SERAPHON PRIEST units are the Skink Priest, Skink Starpriest, and Engine of the Gods, but with the right command trait you can make any skink general a PRIEST and learn a prayer.
Arcane Meteorite might need to be a 7+ to cast. I originally wrote it as "arcane bolt with no LOS or range" and a 6+ was appropriate for that. After adding the 10+ casting mechanic it seems to be a little bit too potent.
Foresight can stack with other -1 hit effects, like the Priest prayer. Reducing hit rolls is extremely valuable at stopping units like Skyfires and Longstrike Raptors that get bonus effects on hit6+. That said, Foresight may not be powerful enough to compete with the other options. I can try changing it to work in all phases, not just the shooting phase.
I have some custom warscrolls in the works that add things like a Kroxigor Hero, Ripperdactyl Hero, and a Skink Chief on a Troglodon. If anyone is interested I'll post them here later. I don't want to steal Bowser's thunder; I had no idea he was also working on a similar project