Snails and DIY Background

Hello! I have two aquariums with DIY styrofoam backgrounds, covered in cement, then sealed with a waterproof concrete sealer. Since I had two mystery snails die last year from ingesting some of the coating from a broken pot I put in their tank, I'm wondering if I can even have snails in those tanks.

I've had four nerite snails in one of the tanks for three weeks, and so far they haven't even been on the background, but there is no algae on it for them either.
I would really like to put either a mystery snail or rabbit snail in the other one; but I'm not sure if it would be safe for them.
Has anyone had experience putting these types of snails in with a decoration like this?