i had similar problem.
(correct me if i am wrong as i am a newbie) the way you suggested will change the language of front page and direct to frontpage every time the lang is changed but not the CURRENT page displayed inside the wrapper. I would like to have the current page translated (of course not necessarily by joomfish).
eg, my application inside wrapper will change lang based on parameter as below
is it possible to have joomfish passing a parameter as similar to the above? if not, where could i retrieve the current lang selection value so that i could modify my application to change.