Other refinements: each person is randomly permanently assigned either: blue/green OR they see blue/green but it’s actually green/blue behind the scenes. This makes any explicit discussion of blue/green more difficult.
Or: Each person actually has grue and bleen buttons. At some time t, they are suddenly voting for the other colours. An extended form of this looks similar to your ETA.
Other refinements: each person is randomly permanently assigned either: blue/green OR they see blue/green but it’s actually green/blue behind the scenes. This makes any explicit discussion of blue/green more difficult.
Or: Each person actually has grue and bleen buttons. At some time t, they are suddenly voting for the other colours. An extended form of this looks similar to your ETA.