If you wish to capture a Name & Surname both in uppercase please type regex(.,’[A-Z]{1}[a-z]{1,50}[ ]{1}[A-Z]{1}[a-z]{1,50}’) under the constraint column of your xlsform.
Please note that you are able to type only 50 characters for Name and another 50 character for Surname. If you wish to have a much more longer one increase the number to your desired one.