But does anyone knows what would happen if a plugs adapter is wired wrong?
Reversing the polarity on the headphones should have no effect*. The same (probably) goes for the microphone outputs, as most amplifiers are AC coupled. Reversing the external DC supply could be problematic. As in the headset electronics won't work and might be damaged.
*Reversing the headphone polarity at some point inside a noise canceling system (not at the GA or XLR interface) could render that system non-functional.
