There's a TWLight message at https://github.com/WikipediaLibrary/TWLight/blob/production/TWLight/users/models.py#L687 , which says {wp_username}. Its documentation says Translators: Do not translate. AFAIK, there's no good way to mark gettext message as ignored in translatewiki, but I might be wrong.
Is it possible to remove it entirely from translatewiki somehow?