I am importing historical data into CiviCRM where there is the field privacy accepted and the date of acceptance. How can I assign these values in the import? It seems to me that this cannot be done manually either.
I'd create a "Data Privacy Acceptance" or "NDA Signed" activity type or something similar and do an activity import with a status of completed and the date they accepted it.
You will need to match the newly created Contact ID back to an activity import file to do the activity import. You can use the external ID field from your legacy database to do a match (vlookup).