I currently working on a translation project for phabricator. Extracted all the string with i18n binary and created the translation classes.
If a string is empty (null by default) tha `PhutilTranslator::translate()` method returns an empty string.
It is no so easy to make translation, I recommend to allow translate() method to return the original input (`$text`) if the translated string (`$result` in this case) is empty.