I installed rawtherapee instead and it is definitely much better. And it actually works lol.
FWIW, I think I have fixed rawstudio build (won’t start PowerMac now just to verify, but I reproduced the failure on Sonoma and then fixed it, so provisionally it will build): https://github.com/macos-powerpc/powerpc-ports/commit/797dd6a03f471d8cc1ee5b50064f2a9906ce03be
But rawtherapee is the best of what works at the moment. (I could fix the build of darktable, but it crashes on launch, LOL.)