They're looking good so far.
I used some very old decals in an old ESCI F-5E kit not long ago, but sprayed them with a clear coat before use. Most of the decals I needed from this sheet worked without problem, although they took a little longer to release from the backing paper, and only a couple of the unimportant stencil decals either broke up or dissolved. I had no problem at all with the more "solid" decals.