What happens if an employee retires during the covered period, does if affect FTE reduction?

No, that is voluntary separation.  “FTE Reduction Exceptions: Indicate the FTE of (1) any positions for which the Borrower made a good-faith, written offer to rehire an employee during the Covered Period or the Alternative Payroll Covered Period which was rejected by the employee; and (2) any employees who during the Covered Period or the Alternative Payroll Covered Period (a) were fired for cause, (b) voluntarily resigned, or (c) voluntarily requested and received a reduction of their hours. In all of these cases, include these FTEs on this line only if the position was not filled by a new employee. Any FTE reductions in these cases do not reduce the Borrower’s loan forgiveness.”