"I’ve listened to it a few times and can’t put my finger on what all the fuss is about. Perhaps I’ve missed something?
what parts did Sanderson most regret going public?"
Mark Sanderson made clear that the GB is about money and not about love.
Mark Sanderson made clear that the WTBT$ is about a business corporation and not about Jehovah God.
Mark Sanderson made clear how hypocritical he is.
Jesus exposed Mark Sanderson and the GB and the WTBT$, just as foretold in Luke...
"...the leaven of the Pharisees, which is hypocrisy. But there is nothing carefully concealed that will not be revealed, and nothing secret that will not become known. Therefore, whatever you say in the darkness will be heard in the light, and what you whisper in private rooms will be preached from the housetops." (Luke 12:1-3)
"No servant can be a slave to two masters, for either he will hate the one and love the other, or he will stick to the one and despise the other. You cannot be slaves to God and to Riches.” Now the Pharisees, who were money lovers, were listening to all these things, and they began to sneer at him. So he said to them: “You are those who declare yourselves righteous before men, but God knows your hearts. For what is considered exalted by men is a disgusting thing in God’s sight." (Luke 16:13-15)
Jesus will keep exposing the GB and the WTBT$. They can't hide from him.
https://www.jehovahs-witness.com/topic/6047055877767168/transcript-mark-sanderson-john-ekrann-auditing-audio