[Daryl]

I feel like such an idiot, so like I bet I am supposed to trace that plane line on the back swing as well? The magic of the right forearm deal thing that has been talked about endlessly here?

Time to head back to the idiot box............

Whoa. You may not be wrong. Tiger is on the Elbow Plane so his forearm is On the Swing Plane because his Elbow and #3 PP are On the Swing Plane.

Look at the Blur of your Clubhead in the Above Picture. You may be on the TSP? If so, though your #3 PP may be tracing the Plane Line, your Elbow and Forearm may not be On the Swing Plane until Impact. What's important is that your Right Forearm Flying Wedge is at Right Angles to the Left Arm Flying Wedge. It's important for the Right Forearm Flying Wedge to be at 90 degrees to the Plane of the Left Arm Flying Wedge.

FLYING WEDGES Example – multiple sails on a sail boat.
Mechanical – Push-Pull rams on hydraulic excavators mounted at 90 degrees to each other to position and hold the main beam.
Golf – Maintaining the constant simultaneous In-Line relationship of the Clubshaft with the Left Arm and the Right Forearm positioned at ninety degrees to each other along the Line of the Left Wristcock and the line of the Right Wrist Bend.

Therefore, if your Left Wrist Cock is on the TSP, then your right forearm/elbow angle looks correct at this point in your Downstroke. If anything, you might be slightly Under-Plane.