I have the same problem.
In the Applicability I have tried...
LeaveApplicationRejection.EmployeeSC=LoggedInRegularUser.DisplayName
Does not work.
tried....
LeaveApplicationRejection.LeaveApplication.EmployeeNameSC=LoggedInRegularUser.DisplayName
Does not work
tried....
LeaveApplicationRejection.LeaveApplication.Employee.DisplayName=LoggedInRegularUser.DisplayName
Does not work...Reference Error.
Certainly looks like a bug to me
However...finally found a workaround (but would like the bug fixed.)
In my BO LeaveApplicationRejections I created a text Attribute called EmployeeDisplayName and set it with a rule on the BO
LeaveApplicationRejection.EmployeeDisplayName=LeaveApplicationRejection.LeaveApplication.Employee.DisplayName
then in the Applicability....this works.
LeaveApplicationRejection.EmployeeDisplayName=LoggedInRegularUser.DisplayName
Go Figure!