"This suggests that the lateral rockets OVER compensated for the drift and shot Spirit back in the direction from which it came."

Wait, don't the lateral rockets fire just before the lander-bag assembly detaches the chute? So the lateral rockets fire before the bag assembly touches the regolith, so the laterals wouldn't explain change of course after the first bounce

I'm no aerospace engineer, so its quite possible I either misunderstand the rovers contruction and normal function, or I misuderstood your post and illustration. But IF I am correct in my assertions, I would look towards wind and the unpredictable bounce of the spining tetrahedron of bouncey-bags to explain the end-of-path noise.

I would imagine that its like a football after kickoff. The first bounce is mostly on with what would be predictable for a round object, but the last few bounces go all over the place as the tumbling of the irregular shape exerts enough force to alter trajectory..

Davin L.