I don't have any advise for you but good luck with your plants.

You could try one of those humidity clear covers that are sold at hardware stores. I don't know if they are sold individually or if you need to purchase the tray and cover together.

Sprinkle some red pepper flakes around the seedlings. Hopefully that will repel the cats.

I know outside they use ivory snow powder on plants but not sure as STARTING seeds usually cats don't like cedar like you would hang in closets could maybe get the cedar and hang above plants??

I've kept mine away by putting moth balls around things but they are poisonous if eaten. Also I have placed pinecones around plants to keep them away- my cats won't walk on them.

This is basically what I was going to say. Granny would sprinkly black pepper on her plants, the finer the grind the better, so that it is lose and easily goes up their nose when they sniff it.

Double stick tape barrier. They will NOT walk on something sticky.
;)

The chili pepper thing works but only as an after thought. Cats associate this with that and won't figure it out until they go back a few times and by then the damage is already done.

I seem to remember someone posting that cats don't like citrus-maybe try that.

Just put the plants up high enough that the cats cannot get to them. Top of a dresser, tall bookcase, even top of the fridge unless they can get there from a counter top. Out of sight is out of mind for them. Red pepper will harm cats and I'm sure you don't want to do that.