Foam is what "all composite" means most of the time. The marketing lingo is confusing, but lots of times, in many boat brands, the wood in the older hulls is just as good as the "composite" in the newer ones. Pretty much anything in a transom, if not sealed properly is gonna have issues. I've never built a boat, but I know as long as boats have been built transoms have failed.

Glad you are back on the water!