Only individuals can commit mortal sins. Each one of us wil be arraigned before the Seat of Judgement on the Last Day to account for our own sins. The Church, however you conceive it, cannot be held accountable before God, The hierarchy is composed of individuals so cannot and will not be held to account collectively. How is this so difficult for you to understand? Are you saying that one sinful bishop condemns the whole episcopate to hell?
The binding and loosing did not give the Church carte blanche to decide what is true and what is false. This binding and loosing was a guarantee that the teaching of the Church could never be in error, i.e. never contradictory: nothing  that was bound in heaven would ever be loosed on earth.
Your concept of the Church defies both Faith and reason: examine it.