Can I edit the wording of the messages?

Partly. Bulk announcements are written by you, word for word. Automatic messages — invoices, reminders, payment confirmations, schedule changes — use fixed forms that insert your school's data: student name, class, amount, and dates.

That limit comes from the official WhatsApp route, which only permits registered templates. What a school does control is the sender's identity: every message names your school and closes with your school's signature, not Klasku's.