As you know, both FIRPTA and the State of Oregon may require tax withholding on the proceeds of a property sale if the seller is someone who does not live in the US (legally-speaking) or in Oregon. The forms are messy, as most governmental forms are, and they can be hard to fill out. This is especially true if the seller’s English skills are not perfect.
This does not mean that you, as the seller’s agent, should fill out the forms. If your client can’t figure out how to complete the forms, send them to an attorney or CPA for help. If you fill them out and you do so incorrectly, you may end up being liable to pay the tax. And I bet your E&O coverage doesn’t cover tax liability.