In langify you can publish and unpublish your languages and theme individually. So it is possible to work on new themes or translations without affecting the live store.
To publish/un-publish your language, simply go to:
Dashboard > Languages > publish/un-publish
This is very useful when you are setting up a new language on a live store, and you want it to be displayed once ready.
To publish/un-publish your theme, simply go to:
Dashboard > Theme settings > publish/un-publish
Comes in very handy if you are changing or updating your theme while keeping your translations live.