The wiring of the Erupts cable is interesting…
One interesting thing is that both 2.5mm are connected to both channels, the cup is the one that takes the channel it needs. You can plug the cable reversed and still have the channels correct.
What the mod I propose does is to change the right cup from taking the signal from the ring to take it from the tip (like the left cup).
You can get a custom made cable that works properly, but I think changing the pinout of the cup to the same used by others is a better idea.