When the 270 contains any of these fields, first name, last name, date of birth, and the member is not found, does the 271 need to return those fields along with the AAA error?
We interpret as yes we are required. Per IG required unless a rejection response is generated AND this element WAS NOT valued in the request.
Yes, your interpretation is correct. The 271 needs to return first name, last name, date of birth from the 270 along with the AAA value appropriate for the error.