Pardot admins can choose to set prospect default and custom fields with predefined values to be validated on import.
This defines what data should be validated in conjunction with where it will be saved.
You could manually copy and paste the constraints between the two, but that's a very error-prone approach.
Instead, make use of Grails' global constraints and import mechanism.
The compare validator can only be used to compare strings and numbers.
If you need to compare values like dates you have two options.