Currently you can only translate the R3 UI within a single file. Applications within R3 do not have this feature yet, but we have already worked out a concept for it and will release it in a later version. To translate applications, like 'Tasks' or 'Shift', in the current version you have to translate all components like attributes and forms manually in the builder.
If you want to translate the R3 UI, we would be very happy if you could send us the translation file so that we can include it in the next release and make it available to the whole community.