Charset is not an issue, OpenXcom uses Unicode so any possible character can be displayed.
Font size is tricky. Original X-Com uses 8x9 for small font and 16x16 for large font, and while we can increase those if necessary, it might not fit in the original interface anymore. Although asian text usually has less characters than western text so it might work out?
In any case don't feel it's wasted effort, the text isn't changing anytime soon and with enough experimenting we'll work something out.