Attached to this post is a useful utility that can greatly assist when updating a translation to a SmarterTools product. It will take as inputs the current en.xml file for the product, as well as your translated xml file and compare them.
An output file will be created that duplicates all the data in your translated file, and also inserts any missing keys with their English text. To make it easier to find untranslated areas, a line like the following will be inserted before each tag that was previously missing:
<!-- !!! Missing Translation !!! -->
It is a very basic utility, but does its job well. It has, however, no error detection, as it was written in roughly 15 minutes, and if you try to break it, you will be able to.