I have not read the API usage yet.
but I event have not really put it work, I have not set Redirect translation method,
just 'Operate with GTranslate Pro' option On.
it runs only 2 minute at http://www.cantonfair.net/zh-TW
and it does not work.
the most strange thing is
when I edit translation by hand, it only succed 1 time at this morning,
by now, every time edit , it appear fail.
I set cache folder 777 by chmod -R 777 cache and even chown -R apache.apache cache