My understanding to this is that Pega "PCS722_to_PCS731_Upgrade_Utilities" will import the rules of the PegaPCS-Upgrade ruleset that are used to update the data in Pega Product Composer System for Healthcare 7.22 so that it works in Product Composer System for Healthcare 7.31.
The upgrade utilities cannot be used for the upgrade of your own customized application rules.
After the upgrade is done, first check if PCS 7.31 OOTB features (without your application code) work ok. If everything is ok, then you can run your application and check if all features are still working. If not, you may need to modify your application code to adapt the PCS 7.31 code.