I'd love to have a comprehensive book on JG 2, but the French language is putting me right off. My holiday knowledge of French simply isn't enough to fully appreciate such a book. Hopefully you will release it in English at some point. 500 sales should be relatively easy to achieve.
As an alternative please consider releasing an English text-only edition, to compliment the French book. Perhaps even in PDF format? This way you'd bypass all publishing problems. Just a thought?