I'd definitely write a note and hopefully they'll do a better job informing folks at check-in (at least airport check-in) that food is no longer served in Y on this route. I double-checked some advance bookings and it does appear that the flight has transitioned to the EATS menu. I'm also not sure what roast beef sliders they're talking about as there isn't anything on the current EATS menu like that.

My biggest complaint with buy-on-board meals isn't really the quality; it's average, and it's no better/worse than the free meals were (just wish they had some warm options). The biggest gripe is they frequently run out and on a 9-hour flight, the reality of bringing food on board to eat later is potentially prone to food safety issues. Either you eat early in the flight or you don't eat. Also, in HNL there just isn't a whole lot of take-out options to choose from and this flight departs from the furthest pier, so it's a long walk to any of the restaurants.

I've done F (modified BusinessElite) on the HNL-ATL flight and the food isn't anything more than you see on a typical domestic longhaul. It's a shame that they can't extract enough of a price premium to make this a more premium flight. I'd not be altogether shocked to see the flight axed entirely in favor of the numerous existing one-stop options via SLC/LAX/SFO/SEA. Catch it while you can and bring your meal with you!