[freebeard]

IMO, a rear spoiler is supposed to "spoil" air flow, and therefore increasing the local air pressure upon a surface up stream, to intentionally increase DF.

Maybe, but with only a quick glance, I don't see any real "spoiling" of air flow taking place in the pics, related to my earlier intuitive definition of what a spoiler does.

Gurney Flap/wickerbill: https://en.wikipedia.org/wiki/Gurney_flap

Think of it as an inarticulate trim tab.