Reverse Translation Function?
according to t() documentation you can get translate the string it in any langcode,it is mean you can have reverse translation

my suggestion is 

t($string,  array(), array('langcode'=&gt;'en'));


and as example
stack dont let me use persian character(I write in Fenglish but you read it persian :) )

t('Chetori mehrdad',  array(), array('langcode'=&gt;'en'));

return equal of string ('Chetori mehrdad') in english  if you translate it before form English to persian (How are you mehrdad), this mean 'Chetori mehrdad`(persian) => 'How are you Mehrdad'(english) :)

I hope this is useful at this time ,sometimes the answers is after you need :(