As far as I know the translation is currently in phase 3 of 4 and it is planned to add a possibility in phase 4 to change words like department or help topic and so on.
Since the translation effort is not finished yet, your chance currently is to e.g. take the English UK not US ;) language files which should mostly be in an original / untouched state (at least it was so the last time I checked) and be perfect for you.
You only need to generate the phar file from the language pack files, where I have no idea how it's working, so try to search the forum or take a look at github wiki for that ;)
The language pack files are available here btw: www.i18n.osticket.com