[white hawk]

I'm thinking your post is a question, is that right? If you are curious about transom rot there is only one cure. The basic test is done with an electric drill, but since you have removed a thru hull and found wet wood you can skip the drill test. You could drill a series of holes a few inches apart to find the vertical extent of the wet/rot, but it will only confirm what you already know. The delaminated FG is pointing the way to transom replacement. It may seem daunting now but once you get into it you'll be glad you did and will be rewarded with a near new boat.