This indeed can be a problem. I have fixed this with paper adhering only lightly. I wad up a paper towel and just barely wet it, and blot down on the covering paper. The one I rescued was only stuck in one spot, so I very lighty daubed the wet towel down on that spot. It did wet the decal film slightly but not enough to hurt anything. But it is indeed a risky task. Good luck. I would wait and do this soon before you are going to use decals, not weeks before.
If you do damage decals, maybe you can scan and repair an inkjet copy of the damaged decals.