Apologies for necroing an old thread but I've been playing around with an original S3 ViRGE and I asked ChatGPT whether it could write a small C program that automatically checks and corrects invalid checksums for ROM files. After a little back and forth it came up with the attached which worked for me- much quicker than doing it manually. Included is the C file as well as a macOS (Intel) and a Win32 console versions.

Very useful thank you!