I have a Fuji and i always shot raw + jpeg, that is for sure a good solution, it only wastes a bit of space.
Given this, i convert the pictures i want to print and the ones i think are worth doing so from raw to jpeg, with raw therapee. I use it with xtrans file from 2015 or so, and i have created a profile i consider quite good for xtrans files, especially at base iso, since i most shot landscapes.
Given this, i attach the image, on the top the raw developed with raw therapee, on the bottom the jpeg. Unfortunatly the profile i have created for fuji 15 45 isn’t yet into lensfun, but you can find it into pull request. Incredible optic at 15 even full wide, save for distortion.
A thing that would be great to have would be better chromatic aberration correction, the one that comes with lensfun is “much better than nothing” but also isn’t by far as effective as autocorrection with bayer files.
I don’t know darktable enought to advice something in order to create better exports, save for markenstein 3 pass algo instead of the maybe still default fast algo.