Google announced as part of this video that text that is automatically translated by a computer (machine translated) is webspam. Google does not want to index this content, and it will penalize sites that try to get machine translated text indexed.

If you do get text well translated by an actual human translator, you should put the translated text onto a new site. This can be either a new domain, new sub-domain, or even a new folder. Google does best at indexing different languages when it is set up as a different site. Google usually has problems identifying the language and indexing it correctly when a URL parameter is used like you have done. See: How should I structure my urls for both SEO and localization?.