I have no problem understanding how you rotate your left/right forearm based on your description and how the left hand lies on the inclined plane at the top. However, you have not delineated the difference in forearm rotation between hitters versus swingers during the backstroke and described the exact right forearm alignment at the 10:30 o'clock position in both hitters and swingers.
Jeff.
Prepare to hit a hard pitch shot where you are going to use your right arm to PUNCH the ball with your elbow in punch position. Take the club back and then take it down and stop at release point. From there take the club to the top of your backstroke at 10:30 as you have said.
Do the same thing but this time . . . lead deeper with your right elbow more infront of your right hip ala Pitch Elbow as Homer has described it. Stop. Now take it to the top from there.
Is there a difference in the right forearm alignment? Remember ALL GEOMETRY IS DERIVED FROM IMPACT GEOMETRY . . . including the Right Elbow location/Basic Stroke. So if you intend to have your elbow in a Punch Basic Stroke alignment your Top should comply with that alignment . . . and vicey versey with Pitch. Work from Impact back . . . that's why Fix is so important.