The English teacher is the class teacher, so if I endorse English to the class representative, and I imitate the class representative’s signature, can it usually go unnoticed by the teacher? Even if there is a little observation

As a qualified department head and class teacher, you will definitely know the truth of the matter. Adults also came from students, and it’s hard to get past them with your little tricks. Rather than being embarrassed and uncomfortable then, it is better to endorse it honestly now.

Unless you did your homework well and the teacher pretended not to know.