Hi Aparna
There isn't a program completion upload available to set the completion data in bulk so the program completion date is calculated from the date that the program checks whether users have completed the courses sets required to complete the program. Courses can be completed on different dates and he program can be completed by completing different course pathways so calculating the program completion date from the course completion dates is not able to be done accurately in some cases.
It is possible to adjust the program completion date using the program completion editor and also mark a program as complete and add a date but not in bulk.
This is expected bahaviour and a new feature has been suggested to upload program completion data but hasn't been prioritised.
Regards