Your definition of a "Catastrophic Failure" evidently differs from mine. In my view, if a rifle suffers a parts breakage which renders it inoperable, then it has suffered such a failure. If a firearm stops working, that is a Failure. (to fire). If that stoppage is due to critical parts breakage without which the firearm will no longer function, that is a Catastrophic Failure. When you have a 9-lb "walking stick" along on your shooting trip, you have suffered a "Catastrophic Failure".
I do not view a Piston as a common part found within a field repair kit (which ought to fit in a trap-door pistol-grip). Pistons are a major component that ought not be snapping, and if they are, then it is a design failure. As regards the WK-180, I would have to suggest that the piston is too thin. The much beefier Templar piston has yet to suffer a breakage (to my knowledge), and selected rifles have now well-exceeeded 2K(+) rounds without cleaning and with total reliability.
The Templar is not perfect, but being an evlolved WS-MCR it is 2 generations advanced over the WK-180 which came first and has not substantively changed. The WK-180 suffers from routine Piston breakage, mostly due to loosening Gas Block Retention Screws, where it looses alignment and is forced to flex. This problem is largely avoided by routine preventative maintenance, however when you design a rifle as an entry-level product you have to take into account that maintenance (especially the preventative type), might not be the new owner's strong suit....