[Plugin: xLanguage] Appropiate Filter Hooks to translate image caption, alt and title inside gallery

Hi, I’m using this plugin to translate the website of a friend, however it fails translating the alt & title attributes and captions from images inside media gallerys.
I’m trying to find the appropiate filter hooks, but none seems to be valid. ¿Any suggestions?

http://wordpress.org/extend/plugins/xlanguage/