Due to its inclusion of OpenSSL, MWorks "uses an industry standard [encryption] algorithm, not provided within the Apple operating system" (quoting Apple's documentation). Therefore, in order to be offered for sale in France, we require a "French encryption declaration".
The instructions for getting said declaration point to this web site. When I first looked at this site, it was not at all obvious where I could find the relevant information, so I just gave up and opted not to distribute MWorks for iOS in France. Looking again now, I think the relevant content is under encryption control, but I haven't had a chance to review what's required. If I can understand the requirements, and if meeting them doesn't require an unreasonable amount of my time, then I should be able to get MWorks on the French App Store sometime in the (hopefully not too distant) future.
In the meantime, you should be able to download MWorks from a different country's app store. It's a bit inconvenient, but it's better than nothing.
Thanks a lot for the detailed answer, it’s not what I expected indeed (ah the magic of French admin) ! Thanks for trying if you end up following the procedure. In the meantime I’ll indeed use a different country…