When we initially send the application none of the forms were filled, signed or dated with pen (print --> hand-written --> scan), as in the guide it is explicitly mentioned not to do so unless it is advised. We did everything electronically. When it is not possible to signed electronically (like typing name on the sections 8 and 16 of IMM5768 ), we used adobe reader's fill&sign feature to type the names of sponsor and co-signer respectively. As far as our understanding from reading several FAQs, guide on IRCC website no where it is asked to to hand-written stuff on any form.
Having said that, we received communication to resend the IMM5476 only, no other forms, with hand-written signature. However, recently someone post that s/he was asked to send other forms too, not only IMM5476. So it is kind of random and depends on the officer who is working on our application.