That's odd. So the switcher in your test site does successfully direct a 'site/2014' address to a 'site/fr/2014'-style address? Is there a public test/example site for this plugin, so I can check it out?
I've created a brand new WordPress installation to test this out (with the default theme). Right now, it contains only the Hello World! post, the sample page, and their respective translations (published at the same time), but I'm still getting the same behavior from the switcher if I activate the 'Hide URL language information for default language'.
Here, I've pulled a couple of screenshots from my configuration screens:
screenshots