The French are in their own little world when it comes to music. I've realized this ever since I started following Alizee. Have you ever taken a look at the Billboard charts for France? Remember René la Taupe at the top of their charts?
I don't think it's that surprising that Alizee would struggle with album sales in France. Her fans and market is everywhere but France. You've sifted through her Youtube videos. Probably a couple of hundred million views since 2006 (when Youtube began and after she retired). Most of the comments are in English and Spanish. There are more comments in Russian and Chinese than French. Unfortunately, most of the people enamored with Alizee have no idea she is still singing and just released a new album. I honestly will not be surprised if Alizee's US sales for "5" surpasses her sales in France. And that's with no marketing to her U.S. audience.