Translators often publish and continue the translation by making the translation in draft state. This kind of translations appears in "In prograss" set in dashboard. But they can be deleted by translators. That results a case where the data of a published translation is deleted.
We should not allow deleting a trnaslation if it was once published.
ContentTranslation\Translator::removeTranslation( $translationId );
This is a hard delete and disconnect the translation from translator. That should not happen if the translation was once published. More over, the translation should appear under "Published translations" set
ContentTranslation\Translation::delete( $translationId );
This makes the status of translation as 'deleted'. Ideally the status should go back to 'published' because the translation was once published.
ContentTranslation\Draft::delete( $translationId );
This makes the draft entry hard deleted. Which should not happen because the draft is required for parallel corpora. See T119489: Avoid deleting the saved translation once translation published to wiki