The export process works similarly, you can choose which language in your store to export, and the file to export to. This lets you copy a language from an existing store to a new one. It can also be used if you wish to update strings; you can for example export English strings, get them translated by a contractor (or power translate in Google Docs) and then re-import them to the new language. Or you can use this process to make changes to the English strings and then re-import to update the site.

For minor language tweaks, it will be easier to use the Kartris back end.