Help and ideas needed

If it is only raised a bit then you can use the matte varnish to create a raised textured ares.

I think I would try several layers of thick medium if it was me -this can be colored before applying and would look very natural

You can mix some matte varnish with some odorless thinner and pounce in on with a stencil brush or just a brush with stiff bristles then bake. Give it a couple extra minutes to set. After it cools you can do it again until you get it as raised as you need to and then paint it.

Both of those Ideas should work good and stick on the vinyl after being baked on. I would add a bit of the [Genesis Thinning Medium], to either one just enough to make it workable and apply with brush. You can put it on and then spread it into shape with a round bristle brush. Thin it just enough to where you can move it around with a brush.