Pretty much the hardest part of transcribing the Japanese is, like, the first 100-200 lines--most of the important terms in the movie will have been said by then ('Rebel army secret base', 'Battle station', etc.), so fewer and fewer terms have to be looked up in order to get readings for them. After that, it's just a matter of finding enough motivation to crank out the lines, lol.

Since every line of OCR'd text would have to be checked anyway, I'm not sure how much time it would actually save over just doing it by hand. But I'm definitely intrigued. If it works well, then I might be able to help proof Traditional Chinese, if no one else actually, y'know, knows Mandarin (I know Classical Chinese, and I know my way around Traditional hanzi, but I don't actually speak Chinese, and I'm hopeless with Simplified).