Unless the governor incorporates a yaw rate sensor, anytime you have a rapid yaw rate, you'll have an effect on rotor RPM that will not be what you'd expect. In fact, it will be the opposite of what would happen without a governor.
In the Cabri, if you're yawing with the direction of rotation of the main rotor, you'll climb (if you don't touch the collective). If you're yawing counter to the direction of rotation, you'll descend, and it may be difficult to stop the descent.
Think about the governor as counting rotor blades passing over the tail boom. It wants to keep that constant, and so if you're yawing with the rotor, the governor will think the rotor has slowed down. It adds fuel to get the rotor back to the 'correct' rate of rotation, but this is actually faster with respect to the earth than it appears from within the frame of reference of the helicopter. Hence the climb.
Opposite if you're yawing counter to the direction of rotation.
Could be part of the explanation for the incident.