Originally Posted by CRW
Although the individual bishops do not enjoy the prerogative of infallibility, they nevertheless proclaim Christ's doctrine infallibly whenever, even though dispersed through the world, but still maintaining the bond of communion among themselves and with the successor of Peter, and authentically teaching matters of faith and morals, they are in agreement on one position as definitively to be held.
I think many misread this as Bishop’s always proclaiming authentically correct teachings. However, they must teach doctrine concerning faith and morals that are definitively true; one must remain vigilant.
the passage that you cite refers to the Ordinary Universal Magisterium, i.e. to the body of Bishops teaching in union with the Pope over the course of time. Individual Bishops never teach infallibly. They participate in the infallible Magisterium as a body united with the Pope.