Each employee's leave entitlement for the current absence period will be based on their holiday entitlement template, length of service and contracted days.
This will not be influenced by their term time fraction. Changing the term time values on their salary line will not affect how many days of leave they will have available.
If an employee works part time and you need the system to reflect this on their Absence page, please make sure you've added the correct number of contract days on their profile.