Well, you just need the X axis and Y axis of the square and find the direction they pointing. There’s a pattern you can see with my gif. The square on the side has its X axis pointing toward the same direction as world X. But the Y axis of it is facing down. So with that information we can determine that it’ll be used with XZ axis.
I’m not on my PC but hoping this can help you in some way.
I said Foward Vector as that gives the X direction and Right Vector as it gives the Y direction. But you probably can find that just by getting it’s rotation.
This is all a theory I haven’t test anything. But using the square patterns you should be able to determined something.