The import of translations is currently disabled on wikis running the Translate extension; the import feature is disabled in CommonSettings.php with:
unset( $wgSpecialPages['ImportTranslations'] );
This special page allows bulk import of translations in gettext format.
Provided the extension is secure, I suggest enabling this feature for users in the 'translation administrator' group. The use case here is that some groups in WMF use commercial translation services, and it would be good to have a mechanism for bulk import of translations.
Adding Siebrand. Needs security sign-off, so adding Chris as well.
T59964: Importing an invalid gettext file causes "Fatal exception of type MWException"