Thanks for the info offvoice ! I had noticed the "offert" (gift) banner on them during my last flight in December, and wondered what were so special about them since the whole catalog was free-to-download... Now it makes sense.

Just tried tonight, and it does work.
When launching the app, don't get fooled by the "locked" icon and the message stating that you can only download press 30h before a flight. Tap "magazines" or "newspaper" and it will display the selected section where aforementioned titles are indeed free to read.