Spots on leaves of new cymbidiums

[Cymbidium]

Hello,

I am from germany and quite new in the realm of orchids.

Recently I've bought 4 cymbidiums and just noticed some spots on the leaves and that they start to discolor. One leave also split in half this night.

For watering I am using rain water, destilled water and tap water; I haven't fertilized them until today, except a few times orchid myst spray from groth technology; as it's currently freezing I keep them inside in my cold guest bathroom (~ 16°C), with a window to the west and north;

I've attached a few pictures in the hope that you might be able to provide advice with regard to what's wrong with my new orchids and how to cure it.

Thanks