Canvas-based onscreen keyboard that supports international text?

I need an onscreen keyboard for our Beatron 2000 game (for Oculus Go). There are plenty of these in the Asset Store, and it's easy enough to throw up a bunch of buttons that do the same thing as those, but none that I could find properly support anything other than English.

Does anybody know of an onscreen keyboard that supports even accented letters? What about Japanese, Chinese, and Korean (the other major markets we'd like to support)?

(Note that free is not required; I'm happy to pay for a good solution to this thorny problem.)