Do you have a console installed? If you do not, there should be one on the CD that comes with Sharp ROMs, if Sharp included them the same as on the sl5500. If you do, then to look at that file, type:
more /home/zaurus/Settings/locale.conf
And look at the Language listed. On my early Sharp ROM, the language is not set, so I don't know the syntax to guide you. For orientation to Linux in general, you might check out the resources on my newbies page
http://www.sdjf.esmartdesign.com/new.html for some simple command-line resources.
I am sorry you had to end up with this problem so early, and hope you can resolve it without too much difficulty.
Also type:
cat /proc/deviceinfo/locale
My Z shows "US" on the above, although the locale.conf file has no language info
Post your results and hang in there!
sdjf