At the moment, QuickFile is only available in English and there are no plans to change this.
Certain elements, such as the text on invoices can be changed using the method referred to in this post. However, this is the only place the language can be changed at the moment.
It may be possible to change other elements of QuickFile using things such as the HTML 5 content attribute, but we don’t natively support this. If you have a Power User Subscription, you’re welcome to experiment with this on your own account using the advanced customisation tools, but I can’t say for certain it would work.
Of course, we’ll leave your post open for other users to add their comments too.