The last time I tried it, it just didn't work, after manually doing it. It took me a good while using beyond compare.
My plan is to it manually via the control panel language editor. That way I can be sure it's going to settle in.
So I'm going to run 7.5x and 6 side by side and copy and paste across.
Yeah long winded, but I language file errors can cause all kinds of problems.
Just my opinion.
Not forgetting what an amazing job has been done.