Still not clear why they bumped off 2 persons for one broken seat.
US 800 as compensation is not a small amount, but hardly a high figure considering it is F class long haul that is concerned.
However, the most important here is that CX should make sure passengers are offered to travel either in F or J on same or immediate next flight. It cannot be assumed that time is not of the essence and that everything is fine just because you offer some kind of hotel room. People fly for a reason. CX should in the 12 hours available figure out how to fly the 2 passengers either in F or J, with an added stopover if necessary.