What should I do if the applicant for patent change makes a mistake and the certificate has been issued?

Change it again, but the certificate has been issued. The patent office will not issue another certificate. After the change, there will be a notice of conformity, which will be used together with the patent certificate. You can also apply for a copy of the changed patent register. The information on the copy is changed, but it is also a piece of paper, not a certificate.