I'm with you on wanting to know what happened. I have the left engine to worry about also. The dealership mechanic said he doesn't know why it happened. There was no sign of overheating. He also said , he had never seen this on a 200. I guess my engine was put together on a Monday morning with parts made on a Friday afternoon.
I will offer this, I did notice a change in the sound of this engine about 5 hours before the hole popped through the left side of the cowling. It had a deeper, throatier sound at start up. That was probably when the muffler failed. I did remove the lower and look up the exhaust; however where it failed is covered by the manifold so it couldn't be seen. After that is when the collector failed and burned through the cowling. So if you hear something different get it looked at.