What you said is true : you exchange the number of Drawn and Counted marbles.

However, the counted balls are white on wikipedia. (they are called defective indeed, so on wikipedia, people count the number of bad balls)

There was also a mistake in the part about symmetries, I replaced :
"Swapping the roles of black and drawn marbles" by :
"Swapping the roles of white and drawn marbles"
since m is the number of white marbles