It is 50% likely the drivers switchpack is at fault, the other 50% being the passenger side switchpack.
It won't be the BCU, the errors you've listed have nothing to do with anything other than BMW being pessimistic about current draw from the window motors.
You can replicate this fault by unplugging the passenger side switchpack on any 75 and you will get the same results, I would trial by substitution the window switches and go from there
Brian
