I think it is fine. We often include the principal's signature in longhand, and that signature can be mechanically reproduced.
This Junior High School Diploma is awarded to
WU SHAO HUA, born on the 25th day of May, 1998,
who has satisfactorily completed the Course of Study
as prescribed by the Compulsory Education Law. It is
given in Taiwan, Republic of China, this 14th day of June, 2013.
Yangmei Junior High SchoolHu Liu-Chin
Hu Liu-Chin (signed in longhand)