This page covers more advanced or "work in progress" areas about extension translation in CiviCRM.
See also: Extension Translation in the Developer Guide.
This extension aims to automatically download and update translation files, including those for extensions:
Otherwise you can download the translation files for an extension by using the following URL structure:
For an extension to be added on Transifex, it must be published on civicrm.org and must be validated for "automatic distribution".