The answer is that Adobe Fuji profiles (or Capture One, or DxO) are simply simulations of the Fujifilm simulation. The name is licensed, but the processing is not identical.
There is no magic bundle of knowledge handed by Fuji to those licensees.
That's why Fuji provide an interface which allows you to reprocess a RAW file using the camera processor if you wish to develop using a different simulation. It's also why a RAW file created using for one model of camera can only be reprocessed using the same model camera. The processing is tied down to the ASIC programming in each model - you cannot reprocess an image from an X-T5 using an X-T3 or vice versa.
