Extension:External Data/Getting support
The best place to report bugs is on Phabricator - see How to report a bug. The project that should be specified is MediaWiki-extensions-ExternalData.
You can also put any questions, suggestions or bug reports about External Data at the talk page for this extension. Or you can write to the MediaWiki mailing list, mediawiki-l. (If you write to the mailing list, please include "External Data" somewhere in the subject line.)
You can also send specific code patches to Yaron Koren, at firstname.lastname@example.org.
Translation of External Data is done through translatewiki.net. The translation for this extension can be found here. To add language values or change existing ones, you should create an account on translatewiki.net, then request permission from the administrators to translate a certain language or languages on this page (this is a very simple process). Once you have permission for a given language, you can log in and add or edit whatever messages you want to in that language.