To make all end-user languages available in the Translation Workbench for adding, follow these steps:
- Go to Setup by clicking on the gear icon in the top-right corner of the Salesforce interface.
- In the Setup menu, search for "language" in the search box.
- Choose Language Settings from the search results.
- In Language Settings, find the Language Preferences section.
- Enable the end-user languages by clicking on the corresponding option.
- Once enabled, all end-user languages will become available.
- Select and add the languages you want by choosing from the list of available languages to displayed languages.
- Click on the "Save" button to confirm your selections.
Now, all end-user languages are available in the Translation Workbench for you to use and manage.