Ask HN: How do you do internationalization in your apps?

I worked on several projects with i18n (from the frontend prospective), and all the time collaboration with translators always took a lot of time. We've used external solutions (which was pretty low-level JSON storage), our own internal solution, but still, this friction was really hard.

How do you tackle such problems, so translators could easily change text on their own with the confidence, that they will change only needed parts?