I don't work languages other than English. I do know that there are
tex user groups around the world including China. I have read
discussions about people who were using right to left languages like
Arabic and Hebrew and vertical plus right to left fonts like Kangi.
Nothing in Tex is "supported" in the sense that you can for a fee call
up a hotline for support. But if you choose to use a specific font
for a specific language there are plenty of people here who can help,
and others in specific mailing lists like luatex and Context.
Keyboards are another issue, dealt with at installation time for
whatever flavor of Linux etc. you use. MSWin may present more of a
challenge but it too is used around the world.
TeX is free. I would download it, and then ask for hints here on using
it with whatever language you needed. I use the pdftex variant and the
Context MKIV variant on a regular basis.
For exotic fonts you might employ luatex, Context MKIV or lualatex.
John Culleton