The shader system has been remade since then. These shaders would need considerable work in order to function in Dolphin again. I don't really think this is something you can do on your own, but if he left the source code somewhere, and your coding abilities are up to snuff, you could give it a try.
AMD Threadripper Pro 5975WX PBO+200 | Asrock WRX80 Creator | NVIDIA GeForce RTX 4090 FE | 64GB DDR4-3600 Octo-Channel | Windows 11 23H1 | (details)
MacBook Pro 14in | M1 Max (32 GPU Cores) | 64GB LPDDR5 6400 | macOS 12