Molasses will have a chelating effect on the other nutrients in your foliar spray, if nothing else. Rather or not that actually affect foliar nutrient uptake or not, I don't know. It helps at root level, however.
I've done it, no problems, adding molasses to foliar feed spray. Hard to say if it actually helps or not. It will leave residue, too.
My observations lately on foliar feeding is that plants are just as responsive to plain water for foliar "feeding", so that's all I use anymore.
Leaves are not efficient nutrient absorbers, they have no evolutionary need to be; that's what the roots are for.