Tomas Slancik

Your second attribute create node seems to be creating unreal_material2
Both should create attribute named unreal_material, just with different value for different group of polys

for advection of custom fields you can also use Advect Feedbacks parm in Advanced tab of Pyro Block End, just specify names of fields in feedback cable that you want advected
it will be more efficient as it will use already computed advection lookup

however for Color workflow you may want to also track the alpha or you can call it color_weight and correct it every substep otherwise the advection will likely fade it to black pretty quickly

for a simple example of something like that you can look at Pyro Configure Color Smoke recipe in H21, even though that is just keeping track of the weight and compensates at the end which is risky for longer sims

vellum is a good option and can give you nice natural deformation

the most important thing is to generate a separate proxy geo for vellum sim, usually with unique piece attribute so that you can then point deform the hi-res geo per piece (newspaper)

I'd start with a simple box with a few divisions per newspaper and use tetrahedral softbody setup

to work as a generator in UE I assume you will want to use Quasi-Static simulation type in Vellum