According to ticket 355426, it is an intentional design in the system and a significant design change to identify records that are not updated in an update action.
In this example, there are existing Relationship Person records that flow to the Update action and appear successful. However, gainsight has not inserted a Company Person record within the hierarchy and so they actually ignore the record. There is no way to identify which records are or are not updated in the Execution Log, they all appear successful.
Please enhance Gainsight to reflect in the Execution Log, records failed that are not Updated.