This is my suggestion, don't know if there is anyone else with a better idea but.
In that new layout, that you switch to when you press the right key, just make the same actions in that event sheet again, and add another that when you press left, goes to the previous layout.
I would make an example but I'm at work so I can't right now. But basicly:
Layout 1
Event Sheet 1
Keyboard -> "On right key pressed" -> System - >Go to "Layout 2"
Layout 2
Event Sheet 2
Keyboard -> "On right key pressed" -> System -> Go to "Layout 3"
Keyboard -> "On left key pressed" -> System -> Go to "Layout 1"
Layout 3
Event Sheet 3
Keyboard -> "On right key pressed" -> System -> Go to "Layout 4"
Keyboard -> "On left key pressed" -> System ->Go to "Layout 2"
And so on..
Hope I could help.