In my experience, I think you would find that a standard pollen trap will work better with the smaller bees. They will still lose enough pollen to be useful but won't be as reluctant to go through the trap and not have to work as hard at it. But then my bees are small (4.9mm comb) and my pollen traps are doubled #5 hardware cloth with a gap between them (as I understand, what they call "coffee wire mesh" in Africa), Sundance brand traps and not the star shaped ones. Success and failure is all in the details...
Maybe the African bees are smarter and figured out how to move through it without losing their pollen...