From what i understand : shooting in RAW only shows the selected film simulation on screen when capturing images. Transferring files into f.e. Lightroom shows RAW data where you are able to select any type of Fuji film simulation like Across or Velvia etc...
Correct ?
Not exactly.
If you don't use a JPEG generated by the camera then you forgo access to Fuji's film simulations. They're proprietary and Fuji does not share them. In a raw converter like Lightroom what you're selecting when you apply a profile like Velvia or Acros is Adobe's simulation of the Fuji film simulation.
How faithful/acceptable Adobe's simulations of the simulations are remains a topic for discussion and opinion.
That is false mostly. Although the film sims are made by Adobe both Fuji and Adobe work on them together so they are as close as possible as to what Fuji uses on the JPG side.
Simplest way to tell is set up a test subject and shoot it with both RAW & JPG recording and change the Film sims for each shot. Then import into LR and assign the same film sim to the RAW as was used on the JPG and compare.
I think you will find them very close if not the same.
