Headless Drupal for managing multilanguage resources for Web/Android/IOS apps?
Use .po files that drupal uses for translations and sets it under sites/default/files/translations.

Build a custom module that manage the .po files status as yo need above and move it to sites/default/files/translations folder if approved, assume you have created another folders to hold not approved files.

Fetching any content from drupal will be automatically translated to the language you set by changing the path prefix for example (/en, /fr, /de if you used that method for detection).

Editing the translation strings in single click yo have to read the file and display it in a form for each record as a text field and rewrite the file after submit.

Hope that helps