Ran into a situation for the first time and was looking for some confirmation.

Customer purchases an Official Check with $15,000, and makes the check payable to XYZ Company (non-customer of the Bank). On the CTR, would it be listed as Customer as 2b, and then I would not list anyone as the beneficiary, as the beneficiary would be the payee on the Official Check, which is not a customer of the Bank and therefore I do not have anything besides their name?

Or am I not able to assume that even though the check is made payable to XYZ that it will actually benefit them because the check itself is in my customer's hand, and would instead list my customer as 2a?

Not in my opinion.

My view is that the purchase of the check was completed by the individual in front of the teller (2b on the CTR), on behalf of the remitter (2c). If the individual completing the purchase is the remitter, there will only be one person reported, using box 2a.