Specifically, in French at work (OK = "test passing", "KO" = "test failing"), and in Italian here (scroll down for the history of Russian revolution in hand-drawn cartoons with Italian captions): the very first one has "guerra KO", another one close to the bottom has
Industria pesante OK
Industria leggera KO
How is that "KO" pronounced in French and Italian? What other languages use that meaning of "KO"?