You can translate the RGC client into any language you want.
Roger have done it very easy for us .
So I'll explain how.
First of all go the main folder and go into languages in there you have English.
Copy it and Rename it as the language you like.
Like I've done with Hebrew. enter the folder and in EACH file there is something needs to be translated.
An example go into file Chat.txt
and you've there
"
CHAT_MENU_WHISPER = Whisper
CHAT_MENU_WHOIS = Whois
CHAT_MENU_PROFILE = Profile

"
you see the part where it says "Whisper" translate it to your own language
it should be like this after you've done.
CHAT_MENU_WHISPER = yourlang
CHAT_MENU_WHOIS = yourlang
CHAT_MENU_PROFILE = yourlang.
yourlang= your own language.

do it to every file should take around 15 minutes maybe more depends on how fast you type .

Here is a made file with Hebrew only ( my main language).
http://www.mediafire.com/?2qbzmdtyyuh
If you need any help ask :P.