How would I use EntityFieldQuery->fieldCondition() or similar to filter by field language? E.g. give me all nodes where field_description has items in English, or in LANGUAGE_NONE?
There is a
$language_group parameter, but I think this won't do the job..
Background: I would like to improve entity_translation module for D7, see https://www.drupal.org/project/entity_translation/issues/2852983#comment-13039403