The hard part isn't so much writing the code as it is testing the code. The WINE server is decades old, porting API calls to another kernel isn't an entirely new or novel process. Getting all the software to work right is an ongoing process though, and it requires careful deliberation over what works and what doesn't. WINE code is still being refined to this day in response to new titles and old bugfixes.

So, I won't preclude the idea of AI helping, but I think human effort is still the bottleneck for projects like this. Even if AI could write perfect code 100% of the time, testing and troubleshooting would probably still be the larger timesink.