Im was thinking about a feature, which i think should be very helpful.
When using translations files for translate plugins and themes to other language, then it should be able to automatic fetch new updates.
We should be able to review the updates and choose if we want to use them or not.
This would also be useful while waiting on a completed translation, so we can have the first part and when new string are ready we just update and new translated string will be added to files.
Hope that other than me could find this useful.