Language does not care about the hardware, but it is a valid Ubuntu question. This is just a guess based on what I’ve seen, but I think if you are able to use a UTF-8 character set (includes most Latin languages), then you probably won’t run into any of the particularly difficult problems (compare that to characters requiring two bytes and perhaps flowing over the page in a different direction than left-to-right/top-to-bottom). Basically I’d suggest researching changing language for Ubuntu to see what happens.
I’m not sure what the JetPack limitations are, but the JetPack installer itself has been known to have issues with spaces in file paths. I doubt anything in UTF-8 would be an issue other than that space in the file path. How well JetPack deals with other languages beyond this I don’t know (obviously JetPack has almost all testing from en_US.UTF-8 users).
Btw, JetPack can be run for no other purpose than to add packages. You don’t have to flash with it, and there isn’t really any risk of messing things up. Sometimes there is confusion when the person installing does not realize that JTK1 must be selected…JetPack supports multiple hardware platforms.