The only reliable raw converter that can handle Fuji color is Capture One. But they have collaboration with Fuji, I don't believe that conversion algorithm is open sourced.
But it would be interesting if AI coding agent could potentially reverse engineer the algorithm.
Like the native Fujifilm software, this does not do raw conversion itself. It uses the processor in the camera to do the conversion.
Doesn't Adobe Lightroom these days also have proper RAW conversion and the Fuji film simulations?
The implementation used by libraw is just as good. Lightroom on the other hand is trash and wormy.
I always recommend RawTherapee for serious photography work. In addition to having been (at least originally) written by a complete colour theory geek and featuring a treasure trove of knowledge in the form of its companion RawPedia, it supports a whole host of raw formats, X-Trans RAFs among them (although Foveon X3Fs regrettably still an open issue).