Not saying that would work better, but it's something I thought would be cool.
Was covered in Lifehacker here: http://lifehacker.com/5907432/language-immersion-for-chrome-...
Seems like it's broken now though. I have a hunch he was trying to use Google Translate without paying for their API. Either that, or he really was paying for the API which is unsustainable for a free extension.
I don't think it's a great idea anyway. If you want to learn French, you should read French written by a native speaker, not a machine translation of English into French. Readlang uses machine translation as an aid to understanding native texts, which is far more acceptable IMO.