@glook Thanks for the diagrams. Mine came with no papers at all and I followed the joystick orientation from the video (obviously wrong). My wiring was correct, but one joystick was mounted upside down. Knowing the joystick connector is "down" I could see which joystick was mounted wrong. It was strange it was always flipping the last configured joystick. All is working now :)
CSL should use CSR chipset, I‘m using the same! Before I tried a Digitus dongle, also CSR. As it didn‘t fit in Superpi case because of its size, I removed housing of both and both modules look quite similiar, just the CSL has a very bright LED compared to the Digitus ;) Also MAC adress tells me it‘s from the same Chinese manufacturer.
I also tried an Asus dongle with Broadcom chipset, but here I had same problem like with Pi3 B‘s internal Broadcom chipset: Inputs where much too sensitive, for example at steering at Mario Kart.
But as discussed, also tried with internal Broadcom chipset of Pi3 B+ in beta and there it seems work fine. (Not too sensitive and also no known input lag of Pi3 B)
So I hope there is a final version for B+ soon too. I‘m really looking forward because for me there is no real alternative to the really good, new 8bitdo controllers!