I want the process variable type to be updated with the current version of CDT f

If I understand your requirement correctly, I think the second reply should help you with this:

"For example, if the target model has a PV (`pv!person`) of type Person^2 and the source model has the same PV but of type Person, the process will not upgrade because the CDT types are different."

Therefore a possible solution is to add add a process variable of the new type leaving the existing one pointing to version ^X of the CDT then remap nodes to point to the new variable which will be indeed of the updated verison.

For backwards compatibility in processes Appian doesn't let you update Person^2 to Person since there can be places where the mappings to fields won't match.

If I understand your requirement correctly, I think the second reply should help you with this:

"For example, if the target model has a PV (`pv!person`) of type Person^2 and the source model has the same PV but of type Person, the process will not upgrade because the CDT types are different."

Therefore a possible solution is to add add a process variable of the new type leaving the existing one pointing to version ^X of the CDT then remap nodes to point to the new variable which will be indeed of the updated verison.

For backwards compatibility in processes Appian doesn't let you update Person^2 to Person since there can be places where the mappings to fields won't match.