So, unfortunately, this didn't work at MGallery St. Ermin's. This was despite me being very careful to make sure that I chose the place "owned" by Accor on Facebook for my check-in.
I have just received my first bonus points from A|Club places though. I've just had an email congratulating me on earning my first badge: the "Welcomer" (sic) badge. The reward attached to this accolade? 50 A|Club points.
I'm hoping that other badges will carry more significant rewards.