Reed Solomon codes, or forward error correction is what you’re discussing. All modern drives do it at low levels anyway.

It would not be hard for a COW file system to use them, but it can easily get out of control paranoia wise. Ideally you’d need them for every bit of data, including metadata.

That said, I did have a computer that randomly bit flipped when writing to storage sometimes (eventually traced it to an iffy power supply), and PAR (a type of reed solomon coding forward error correction library) worked great for getting a working backup off the machine. Every other thing I tried would end up with at least a couple bit flip errors per GB, which make it impossible.