Edit: Thanks for the filepack! I'm working on mskill, so it's missing there, and it has a special characters too. I'm gonna give it for your edits after it's completed (it's a big file, so it may take awhile, but we have eboot and charhelp awaiting further translation)!
I'm sticking to the idea, we should release "exe" patch to Start.dat, and then say, if anyone wants english background, replace japanese BU, BG.. with english ones. Not it would be the most user-friendly solution, but we'll minimize our copyright infrigement, let's do it clean, if it's possible