doubt about two minesweeper gadgets
Since the figure is otherwise mostly symmetric, I believe the 3 I mentioned two sentences ago should be replaced with a 1.


Indeed, the 3 is obviously a typo.


  However, even if that is done, I do not see any way to determine the status of the zs even after...
  
  Am I missing something here?


After $r$ is revealed:


If it was a mine, you can reveal the numbers on the fields occupied by $r'$.
If it was not a mine, you can reveal the numbers on the fields occupied by $r$.


In both cases, you can deduce the status of the $z$s from the revealed numbers.