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I looked into this when we made all the shattered worlds improvements but unfortunately the quick chat system doesn't support localised integers (comma for UK/US, full stop for German etc)
Perhaps you could build that in, then? Localised integer functionality is quite easy to implement in any application in any programming language. You could probably do it without any help from the engine team at all! If you need any example code or help, let me know.
We have localised integer functionality, it just isn't supported by the quick chat system. I can put in an engine request for it though when I'm back in the office.