A server-side mod that allows you to customize any advancements look in chat, and what commands will be executed when the advancement is granted.

  

 

Here's how the config structure looks like:

Each json object inside the file is an advancement:

 

• The key is the advancement id.
• The "message" property has as value the message that will be displaied in chat, uses vanilla chat formatting and Placeholders for ${player} (The player's display name) and ${advancement} (The advancement display name and hover description).
  
• The "command" property has as value a list of commands that will be executed when the advancement is granted, uses Placeholder for ${player} (The player's display name).
   

  

  You are free to use this in any modpack!