Hi Marc,
With the help of Google Translate also you can make bilingual for your store.
Refer the link: http://docs.shopify.com/manual/configuration/store-customization/currencies-and-translations/translations/how-do-i-add-google-translate-to-my-website\
Would be great if we can discuss further on this on Skype. My Skype id is imran66khan
Please share your id to interact further to take this forward.