Stage five could have been called verification, and calling it that would have cost the model most of its meaning. Verify is a quality-assurance word. It asks whether the thing the system did matches what the system was asked to do, and it is satisfied by a check the system runs against its own record.
Reconcile is the word an accountant, a controller and a materials planner have each used every month for thirty years, and they all mean the same operation by it: take what this system believes, take what something outside this system says, and account for every difference between them. It carries the two things verify omits. The consequence is recorded, in the ledger and the stock position, not in a log. And the record is proved against the world outside the system, by the bank statement, the supplier invoice and the count on the shelf.
The vocabulary was already correct, so the model borrows it instead of inventing a term. Confirm the intended outcome actually occurred, record the consequence, and prove the record against the world outside the system. A system that cannot do that has no basis for the claim that it owns any outcome at all, which is why the stage keeps the older and more demanding word.