Reporting back. I was in the 2F lounge between 13:30-14:00 and then again between 18:30-19:40.
During the first visit, the bistro area was deserted (no staff seen there either). A menu was still shown displaying the dish served there (presumably earlier), I forgot to photograph. At the main buffet, delicious warm food was still available, so I wasn't left hungry. As I was leaving, a staff member was wrapping tortillas with smoked salmon behind the bistro counter.
During the second visit, no food was served at the bistro counter, although there was a small buffet station with soup and some pastries. However, a cocktail menu was shown this time and a lady behind the counter was making cocktails, so I did get to thoroughly enjoy the bistro experience
At 19:00, warm food for dinner was brought to the buffet, but still no food at the bistro. As I was leaving, the bistro area was becoming quite busy with drinkers.
So the bistro food experience evaded me yet again, but this time I did get to enjoy some cocktails in a lively atmosphere.

Cocktail menu

"Le Corse"

Ready made mojitos and some cocktail sans alcohol at the counter

Soup from the buffet

"L'audacieux" - ouch, had a lot more ginger than I had expected

A sampler of warm meals from the buffet:
Shrimp with lobster sauce, cauliflower, wild rice and sauteed lychees
Pulled duck and mashed potato (bottom left)
Celery risotto with pickles and buckwheat chips and a hint of truffle (bottom right)

Cocktail ingredients being shown to me