Bangkok was a route that was quickly slipped in under the radar and in all the years that I've been flying I don't recall ever seeing a crew member with Thai language designation. The issue presumably is that there are too few to crew the flights on a consistent basis (this has happened with other flights requiring route language). Adding an additional language for formatted announcements is also a very detailed process. The loads appear full and not sure why the season was shortened. Perhaps they are testing the waters and cannot say with any certainty.

As far as Thai food goes..
They board an awesome Thai Green Curry Chicken out of Amsterdam and certainly a proper route dish should be boarded ex YVR.