Mollies like salt, they actually need a little to flourish.
Salt with plants and corydoras I dont believe at all, I use it and have both in all my tanks(6) my corydoras swim thru the plume it emits when it dissolves in water.
My ghost shrimp were fine with salt, the thing with salt is to have a constant minimum level in there or none at all. I only speak from what Ive had first hand with and I use this stuff monthly. I use 1 tbsp per 30g, it keeps it in there but minimal and well Ive never had any disease in these tanks. None.
I had fish deaths and illness alot when I didnt use it at all.