Okay, real quick. Looking at the engines from the front of the aircraft, the right hand engine rotated clockwise, the left hand engine rotated counter-clockwise. Yes, this was a safety feature, if one engine failed, the remaining engine would not attempt to roll the airplane quite a badly as it would have if they were rotating in the opposite direction.
How? Say you were looking at the airplane from the front. The left hand engine is out, the only one turning is the right hand engine. The right hand engine is now the only one keeping the aircraft aloft, and any rotational forces being applied to the aircraft are coming from that motor, (and propeller) The prop is attempting to twist, or rotate the entire aircraft around the axis of the centerline of the prop. If it could, it would cause the entire aircraft to rotate in a clockwise direction. But! In order to do this, it has to lift the entire left side of the aircraft. The same holds true if the right hand engine goes out, and the left one is the only one turning. In order to spin the ENTIRE AIRCRAFT around the axis of the propeller, it would have to lift the entire right hand side of the aircraft. Let's turn the props in the opposite direction. If the left hand motor quits, (and is no longer providing power to keep the left side of the aircraft up) and the right hand motor is spinning in a counter-clockwise direction, the remaining motor is attempting to spin the ENTIRE AIRCRAFT counter-clockwise around the axis of the prop. In other words, the aircraft is attempting to spin counter-clockwise, (because of the dead motor on the left hand side) and the prop is also attempting to spin the aircraft counter clockwise. Disaster can only ensue. As for the cranks and camshafts etc. etc. The Allison V-1710 aircraft
engine was designed so that the crankshaft could be used on either side, simply by taking the crankshaft out, reversing it, and reinstalling it into the engine. It could then be run rotating in the opposite direction. Remember, IT WAS DESIGNED THAT WAY! Using a symmetrical firing order. (It would fire in the correct order, as long as the cams were reversed as well.) Genius. (p.s. here is a link to a youtube video showing a P-38 start-up, and then shut down. You can easily tell which direction the props are turning on start-up.)
https://youtu.be/mBL6EcyZ9Xk