Josiah,
When I refer to "Church" in reference to your beliefs, I am doing so under the definition you supplied. It was your opening statement that says the entire Church is the arbitrator. I am not referring to denominations.
Now, allow me to address some issues here. We must first look at things from a logical standing point.
Entity: An entity is something that has a distinct, separate existence, though it need not be a material existence.
Rule: prescribed guide for conduct or action
Now, it is impossible for an entity to be held accountable by a rule, it is only possible for it to be accountable to a rule. So, the Church cannot be held accountable by Scripture.
So, if the Church is accountable to Scripture, who then holds it accountable? The answer is that it is the individual who holds the corporate accountable to Scripture. There is no other possible option, as there are only two visible entities in play here, corporate and individual.
Doctrine:a belief (or system of beliefs) accepted as authoritative by some group or school
Dogma: a belief or set of beliefs that a religion, political, philosophical, or moral group holds to be unquestionably true
Now, you can make the claim that sola scriptura is not dogma, but it certainly fits the definition of doctrine and is therefore subject to analysis as such.
For the sake of clarity, in the following, assume "Church" to mean the entire body of Christians.
The consensus of the Church can take the form in two different ways, which are, rejecting a doctrine or embracing a doctrine. Prior to the Reformation, the entire Church embraced the view that the individual was accountable to the Church. As such, it was in the likeness of the Arian controversy. The Church did not have a pre-existing explicit rejection of the new doctrines for the very reason that they had never been proposed before. What the Church did have was a pre-existing implicit rejection of the new doctrines, in other words, the Church's consensus had been to embrace doctrines that were mutually exclusive to the new ones.
At the advent of the Reformation, there were only three Christian bodies: the Orthodox Church, the Roman Catholic Church, and the Oriental Church. All three of these bodies held to a view concerning the Church that was mutually exclusive to sola scriptura, and had maintained it for the previous 1500 years.