To have public messages translated, find the Chat: section and ensure the following is set to true:

Chat:
  # Will try to modify chat to display it in a defined format
  ModifyChatFormat: true
  # When set to true, regular and private messages (excludes clean messages) will have additional information when hovering over it (PlaceHolderAPI supported) and can be clicked for quick reply option
  # To change the default hover over messages seen on sent message, go to your locale file to the Chat section
  ClickHoverMessages: true

Next, find the Colors: section and adjust the settings accordingly. Ensure that PublicMessage, PrivateMessage, me, and NickName are all set to true.

  Colors:
    # If set to true then all public messages will be filtered from color codes and will allow to colorize them with appropriate permission node
    # cmi.colors.publicmessage.[colorName]
    # Colors: black(&0), darkblue(&1), darkgreen(&2), darkaqua(&3), darkred(&4), darkpurple(&5), gold(&6), gray(&7), darkgray(&8), blue(&9), green(&a), aqua(&b), red(&c), lightpurple(&d), yellow(&e), white(&f), magic(&k), bold(&l), strikethrough(&m), underline(&n), italic(&o), reset(&r)
    PublicMessage: true
    PrivateMessage: true

    # If set to true then /me messages will be filtered from color codes and will allow to colorize them with appropriate permission node
    # cmi.colors.me.[colorName]
    me: true

    # If set to true then nickName will be filtered from color codes when player changes it
    # cmi.colors.nickname.[colorName]
    NickName: true

Optionally, if you wish to use Hex colors in your custom join/leave messages, and some other features, you must enable their CMI Module. In modules.yml, find them, and set them to true:

customMessages: true
firstJoinMessages: true
bossbarmsgs, holograms, tablist, etc.