[Mike O]

In 7-3 Homer says that the on plane Right Forearm shows the precise (add "up and down" here) direction it and the clubshaft must take throughout the stroke.

now I know that per 1-L-5 The clubshaft lays full length on a flat tilted plane. So my question is when we turn our hand so that the palm is touching the plane won't the whole right wedge come off and the right forearm go below the inclined plane due to the impact fix degree of bend in the right wrist?

You're correct. The problem you're having is with his writing style. Of course the forearm comes off plane in the backswing. Here are two possible corrections that I would use.

1) change "it" to "hands"
2) change "throughout the stroke" to "initially going back and then again immediately before and through impact".