So it sounds like one option might be retrieving the hs_object_id using the CIF to update records rather than attempting to reimport them.
It may be worth exploring whether we can leverage this to ensure CIF-based updates work as expected.
Another potential workaround is creating a file that includes only the “CIF,” “First Name,” and “Last Name,” while leaving out the “Email” property. This could force the system to check only CIFs, but it would only work if updating email addresses isn’t necessary - though, we would need to update email addresses regularly.