But how do you measure the effective negative gravitional energy of the Universe from observation? You cannot. It requres taking observationally determined parameters and feeding them into the theory - General Relativity in this case.
This is correct, but the pseudotensor approach does not do this. The pseudotensor approach works exactly the same way after the discovery of dark energy as it did before. That is simply not tenable to me.
No, it is not. That is a recreation of the Feynman net-zero calculation, but has the mass of the Universe off by three decimal places. Once corrected, this makes the positive and negative energy contributions equal up to order of magnitude. As Feynman demonstrated.
I have not had a chance to read the Feynman paper yet, but you have to realize that Feynman wrote decades before the discovery of dark energy and the accelerating universe. I am interested to see Feynman's approach, but his mass of the universe may not have calculated dark matter either. There is a good chance Bradford's recreation is more reliable than the earlier work by Feynman.
Now, you can continue to discuss this but I plan to take a break for a while until the libraries open again and the book is available.