Good job Loyce
Side note, have to go dig it up but some coin maker years and yeas ago (Ravenbit? Silverwallet? don't remember) had some code that did something similar years ago. Didn't do the QR just the address on one side and the private on the other on a full sheet.
From a technical standpoint it's a tough decision. If you know the position of the missing characters you can recover a damaged private key.
Once a QR gets damaged beyond a certain point it's gone forever......
-DaveEdit: Since Kazkaz27 is paying a bounty I sent a donation in your name (well at least LoyceV) to a friend (and fellow BTC user) doing a charity event tomorrow.https://www.gentlemansride.com/rider/JaimeCruz560865
Anyone with a prostrate feel free to kick in some $ too it's a good cause. v
-Dave