I was snoozing in the car this morning when I realized: This isn't a bad idea.
Well, not the -warning: Japan- tag, that's just way out there. But what about "Country:" and "Language:" tags? If a book is from somewhere in particular then you can just look at the country tags and go from there. If I remember a book but don't remember anything but the country or language, that could also make my search easier.
This really isn't needed for most posts, I guess, because at least 80% of our total output is from US comics, and in English.