For HMDA, you can report based on a counter-offer without making a loan as long as it is expressly accepted. If you are reporting it as withdrawn, I would report the terms at the time the borrower withdrew. Personally, I would only report as withdrawn here if you had something in writing from the borrower that was crystal clear he was expressly accepting the c/o. W/D days after getting a c/o sounds a lot like he didn't actually want the new terms. Examiners are more likely to question a w/d than a denial on close calls, and you already covered yourself for ECOA.
1003.4(a)(8)(i) - 9. Action taken - counteroffers. If a financial institution makes a counteroffer to lend on terms different from the applicant's initial request (for example, for a shorter loan maturity, with a different interest rate, or in a different amount) and the applicant declines to proceed with the counteroffer or fails to respond, the institution reports the action taken as a denial on the original terms requested by the applicant. If the applicant agrees to proceed with consideration of the financial institution's counteroffer, the financial institution reports the action taken as the disposition of the application based on the terms of the counteroffer. For example, assume a financial institution makes a counteroffer, the applicant agrees to proceed with the terms of the counteroffer, and the financial institution then makes a credit decision approving the application conditional on satisfying underwriting or creditworthiness conditions, and the applicant expressly withdraws before satisfying all underwriting or creditworthiness conditions and before the institution denies the application or closes the file for incompleteness. The financial institution reports the action taken as application withdrawn...
Edit: Started posting before your second post. Sounds like he expressly withdrew for a different reason, so ignore my caution