So I don't think it was a good idea to use the scan form. If they never scan the package, it would be the same as if I never shipped it.
You do have proof that they scanned the scan form, at least. Hopefully, the package will get scanned on delivery.
This is from a Reddit thread in answer to the question:
what does "the acceptance of your package is pending." mean?
"After the shipment is received and Scan Form scanned and the "Package Acceptance" scan done or not, the mail pieces are in transit. These items in transit may not be held up so another scanning can be done. If the scanning did not happen on receipt at the post office they simply move on. Even if they are not scanned as 'accepted' they will continue on their journey. Many pieces of mail end up being scanned as 'Delivered' without having ever being scanned as 'Accepted'."