Many 10 year olds can now edit the numbers as well as the text. I bet document forgers have a little more skill than a 10 year old.
Also by far now, most people use emails to exchange documents so there’s really no fear of forgery.
Anyway, this has been discussed many times before and I don’t want to take your hopes away but I don’t think that that’s on the priority list of the developer. What you can do is this: