Actually, English and German currently are consistent (English: New York Stock Exchange etc., German: New Yorker Börse etc.); but it is up for debate whether those are (translatable) descriptions or (untranslatable) names.
The original Dutch translation was prepared by four people, presumably native speakers:
But that was almost four years ago. In the meantime, lots of new features have been added and some have been reworked, which means lots of additional or updated strings. Since that is likely to continue, maintaining a translation is never “finished”, either; but there will typically only be a few new strings per month or so.