Here is a summary of the trail of reported account information, and required unpdate upon payment.
First, disregard for a moment what is required as to any update of the derogs or delinquencies that have been reported. The first issue is update of the debt status.
Settled means you owe no more debt. There is no such thing as settled with a balance due, if the party agreed that whatever was paid constitutes settlement of the debt. When a party accepts either full or partial payment as a settlement of the debt, the current status of the account shows one, and only one, current status code. Paid. There is no such thing as a current status code of paid or settled for less than the full amount. If the creditor updates the current balance to $0, that is acknowledgment of the debt having been settled. If they creditor does not update the current balance to $0, that means that they have not yet reported their acceptance of the debt as settled.
If you settle for less than the full amount, that fact is not reflected in the current account status. The creditor can choose, at their option, to enter this fact into your CR by reporting a separate "special comment" code to field 19 of your credit file, which simply states that the account was settled for less than the full amount of the debt. That special comment is not scored by FICO, but is a derogatory remark that is available upon a manual review of your CR.
If you have settled a debt, the important reporting is that the creditor update the current account status to $0. That should be the primary focus of any dispute. The status of the account prior to settlement will still be retained in your credit file under a separate reporting code called the payment rating, but the current status has only one permissible status..... paid.
If a debt is settled, the debt collector must update their collection reporting to show $0 balance subject to collection, and close their account. Technically, debt collectors dont report actual debt unless they own the debt; their reporting constitutes the balance of debt owed to the OC that they are authorized to collect. That is why the same $ amount can appear under both an OC and CA reporting.
All of the above refer to what MUST be done upon acceptance of payment as fulfilling a debt. What is not required is any deletion of their prior credit reporting of the derogs and delinquencies that were reported along the way. That is a separate matter that depends upon agreements relating to CR deletions, and is not dependent upon debt status. Those are the fuzzy items. The reporting of the codes outlined above are not. They are required.