So I finally got around to do some editing on these assets.
I translated the menu options, the title (to Train Fill Rate, because that is technically more correct and fits better in the logo) and the subtitles of the DLCs. The subtitles of the DLCs don't make any sense to me (I don't speak Japanese) so I just winged them a bit, but think I figured parts of them out.
Now the question is how to pack these resources back into the game. I have zero experience with how assets are handled in Unity, so if someone can do it, we have an English menu.
Link to the assets (png images).