For the Washington State payroll deductions for Medical Aid Fund, Supplemental Pension Fund, are these required to be displayed on the W-2 Box 14?
No idea, but if you can easily do it, why not? The whole point of Box 14 (IMO) is so the employee does not waste payroll's time helping them do their taxes. If TurboTax asks for the number, there is no chance that they are going to find and total their pay stubs. They are going to make payroll do it for them.