Tomas Slancik

I think you are expecting too much out of it
RenderPass prims are an USD concept which is currently more about simple visibility settings than anything else despite the overloaded name
To make it do additional overrides and changes to the stage at the render time (which is when the Render Pass is used), this would need to be supported by USD, since at that point Houdini and LOPs are out of the loop

if you need to modify the stage stick to context options and LOPs, which allows for quite clean workflows

it likely just follows parent context of the current one (not just a single level up within the same context)
so if you are in /obj/geo1/... no matter how many subnets deep you are still in the same SOP context of the geo1 node, so the parent context is /obj

this is likely a very old feature and also it's a very generic property of panes of any type, so there may be some various uses for various workflows, not sure how useful it is for viewport panes

the fact that the network editor also jumps when this is toggled on scene viewer pane (when they are not linked) seems unintentional to me and I'd also attribute it to this being an old feature

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