ᐅ Masonry Crystallization – How to Achieve a Proper Foundation?

I bought a house where the walls have crystallized. I was told that if I paint or wallpaper here, the crystalline layer will keep showing through.
What can be done without having to remove all the plaster and replaster the walls?
The crystallization is only on the ground floor, as far as I have seen so far. The basement is dry. The moisture came from the roof. On the ground floor, the masonry couldn’t dry out because everything was completely covered with gypsum boards, and no air could reach the masonry to dry it out. The walls are still very damp. I have removed all the gypsum boards to allow the masonry to dry, and I repaired the damaged gutters so no new moisture comes from above.
As I mentioned, I don’t want to break off the plaster and replaster everything. I also don’t want to install new gypsum boards. Is there maybe a primer or something else that can be applied so I can paint or wallpaper over it without stains showing through?
Thanks for the help
Carsten