The createdby and lastmodifiedby is always reflects under "Admin name" in process tasks under manage data even the onboardee was created by other user.
SAP SuccessFactors Onboarding
This is expected behavior and current limitation of the system. If deemed necessary for the business, please submit an enhancement request.
2090228 - How to Submit Ideas for SAP SuccessFactors Products
Manage Data, createdBy, lastModifiedBy, Manage Data, OBX, Onboarding , KBA , LOD-SF-OBX-ADM , Admin UI , Product Enhancement