I have a lvl 65 fire wizard who is now in Stormriven. Would that be or is that too high of a level compared to other Celestia players?
I really believe there is no "too high level" for any world, to low can be, to high never. Celestia can run a bit long in the tooth and being a higher level only gives you the edge to move it a long better.
I personally have been running Celestia with my wizards higher levels so that there is a lot less defeat. On my first wizard there were no side worlds to help level up at so hit there at the right level but was slapped in face with how difficult it was after DragonSprye. I spent weeks just getting past Survey Base area, hated the Grotto and felt I was finally moving a long in Floating Land. With that bad taste in mouth I have never really been a fan of the world and quest at my leisure there as I start a new wizard. I play Wizards for fun and after DS that does seem to be tested.