A payout to somebody outside the United States goes at a reduced or zero rate only when a form valid on the payout date supports that rate — the right form, signed and in hand by then, not yet expired, claiming the right country and article. Otherwise the default is withheld. Treaty moves no money: it reads the payout file and says what may go. The supported rates come from the rate table as you entered it, not from Treaty.
Payees outside the United States only. A payee recorded as a US person is outside Treaty's scope — the W-9, backup withholding and the 1099 belong to Docket, and Treaty will not clear a payout to one. There is no field anywhere in this program for a taxpayer identification number.
A W-8BEN or W-8BEN-E is generally good from the day it is signed to the last day of the third calendar year after that, unless a change in circumstances makes it wrong sooner. A Form 8233 covers one tax year. Which form governs a payout depends on the payout's date — a form that arrived afterwards proves nothing about the day the money went.