Same problem: sometimes I get a blank "Google translation" popup window and sometimes "Application Error - The selected application could not be started...".
All I did was copy the gtranslator.acx file in user store / system/acw/.
I dont know what to do with files for ACX signing: author.p12, sign.sh, widgetsigner.jar
I have the Mobileread Kindlet Kit version 2014.02.14