@neobrain bizarrely, in my testing, this appears to be the case. don't have it set up right now, but i pulled some previous (very rough) benchmark results in the same area of the half-life training course, and the difference was stark (30fps with library forwarding, 45fps without). if you've got a particular title or app you'd like me to test, i can certainly look into that, too!
my best guess for the need of version overrides is that the pi 4b only supports up to openGL ES 3.1 officially, but the rootFS library at least claims to support further. whether or not it actually does i haven't tested yet.