These TGVs have a different menu to the regular domestic French TGVs!
The menu is branded as "b2in", and features the logos of both SNCF and RENFE on it:
A pdf of the menu can be found here on the Elipsos site - if that isn't the exact one as found on the TGV last weekend then it's very very close to that!
It largely contain the same kinds of things as the regular TGV menu, just many of the items are more spanish influenced. For example, they have Spanish beers, and one of the sandwiches features Jamon Iberico. French options were equally present, but most people seemed to be ordering Spanish things out of preference whenever I happened to be in the bar to see.
Quality wise - seemed OK, but not amazing. Not sure if it's better than normal TGV food or not, as I've not tried normal TGV food of late...
Otherwise, there was a small trolley that made the rounds of the seats from time to time, with a subset of the menu available. The staff manning the bar and trolley seemed (from accents) to be a mixture of RENFE and SNCF staff, but all spoke fluent Spanish and French, with many also speaking English and Catalan too.
Oh, and based on this RENFE page on their international high speed services, it seems that the Paris-Barcelona route is the only one served with TGV Duplexes, while the Barcelona-Toulouse, Barcelona-Lyon and Madrid-Barcelona-Marseille routes use Spanish AVEs. It's therefore not clear if the others use this menu too, or if they have the regular Spanish AVE menu onboard.