can glycerin help soften too dry fondant and gummy wilton color gel? what will work to bring these two items "back to life"

I have rescued some gel colours by adding a little clear alcohol, like vodca or gin (a drop at a time). We dont have the wilton gels over here, but Im sure it cant be that different.

As for the dry fondant, it depends on how dry it is, if its crumbly and hard, I dont think there is much you can do to revive it, if its just a little crumbly, but still soft you can try adding a little glucose or even some egg white. A few seconds in the microwave may aslo help, but try a small piece 1st.

A tip an old cake decorator gave me once is to add a cut apple to the bag with dry fondant and then to leave it overnight. I have never tried this myself, but some of these oldtimers tips can be awsome

HTH