That particular bug seems explicitly covered by this cryptography, using the rangeproofs. But if there were ever some other subtle bug that created money out of thin air, would you be ever able to detect it? The schemes mentioned all seem to sanity-check individual transactions, and not accounts or the money supply as a whole.
The article mentions Monero and CryptoNote, for example: https://getmonero.org/2017/05/17/disclosure-of-a-major-bug-i...
And that page says: "This effectively allows someone to create an infinite amount of coins in a way that is impossible to detect without knowing about the exploit and explicitly writing code to check for it."
It seems like a formal correctness proof would be very important for cryptocurrencies with such strong privacy guarantees.