Here is the full list of all 16 Newfound Courage achievements.
Complete Newfound Courage.
Complete the Lorebook.
Make Alex eat sweets till he gets a stomach ache.
Fed Jake and Alex some apples.
Clean up the last book the Blank Sending throws.
Make Alex jump off Deadworld too many times.
Complete the entire Return to Otherwhere DLC.
Fight to the death in the Silverpine Arena.