I have those same spots on a few Catts that spent the Summer on screened porch!
1. Are your spots "rough" on the surface or smooth? Mine are rough.
2. Are they only on the top of the leaves or do they go all the way through? Mine are 99% on top surface.
I've seen spots like that on various non-orchid plants in wet habitat. I'm only guessing, but it might be a fungus only active in very wet and humid conditions.
__________________ May the bridges I've burned light my way.