Three TRAITS and one new ROLE with demonic vibes. All of them could easily slot in against any of the core FIST material.
With a title like “Federal Bureau of Infernal Affairs,” I was expecting to see some info on a demon-focused faction (e.g., a cabal of demons in competition to win the most souls, a secret government organization working to purge demonic influence). While that’s not present in the document, you could use this material as a starting point to build your own.