MediaWiki:Apihelp-query+messagecollection-param-filter/en

From translatewiki.net

Message collection filters. Use ! to negate condition. For example !fuzzy means list only all non-fuzzy messages. Filters are applied in the order given.

fuzzy
Messages with fuzzy tag.
optional
Messages which should be translated only if changes are necessary.
ignored
Messages which are never translated.
hastranslation
Messages which have a translation regardless if it is fuzzy or not.
translated
Messages which have a translation which is not fuzzy.
changed
Messages which have been translated or changed since last export.
reviewer:N
Messages where the user number N is among reviewers.
last-translator:N
Messages where the user number N is the last translator.