The Cagliostro's Secrets Add-on for Steelrising has 6 achievements.
Defeat 30 of the following enemies: Necromancers, Gravediggers, and Apothecaries
Defeat the Scribe using only weapons found in “Cagliostro's Secrets”
Defeat the unstable Automat at the hospital
Defeat the Scribe
Complete the secret area in the Quartier du Temple
Complete “Cagliostro's Secrets”, save Brissot and bring him back to the Cordeliers