I am going to make a guess here and say they're not inverted.
What looks to be happening is a lower surface wing body root
section expanding lower surface toward a thick symmetric foil.
May or may not be best practice, looks good from where I stand.
Not reflexing the trailing edge but having the same effect. The stuff I have read makes it sound like the fuselage creates a higher local area of incidence and flipping the root airfoil brings the incidence back down reducing drag.
I can't see why you'd want to invert the airfoil, but twisting it might make sense. Too much, though, and you get nasty tip stalling characteristics. Reducing the camber inboard might accomplish the same thing.
On a low-wing plane, the spot where the wing connects to the fuselage tends to be a trouble spot drag-wise, as the air getting pushed aside by the fuselage then gets squeezed more when it hits the top of the wing.
Designers do things like tapering the fuselage in where the wing attaches, adding a bit of a strake to the root, or giving it a reverse gullwing so the inboard section has negative dihedral.