OK, so one has to take care when implementing business logic based on the Task Name.
For example, if we had a parallel gateway and there were multiple tasks associated with the workflow instance, any logic based on the Task Name post migration may not be executed.
Well, yes and no. Migration instructions are supposed to map semantically equivalent activities. That is also why we decided to change as little attributes as possible during migration. Perhaps process instance modification is better suited for that use case, i.e. cancel the Remediation Review activities before migration and start new instances of Approve Request after migration. That said, I understand that modification and migration cannot be easily combined via API, especially when using the batch migration feature.