"Einstein's original theory was far more accurate than first thought."
It is not accurate at all. It cannot even predict how light falls in a gravitational field. According to general relativity, the speed of light DECREASES as light falls:
"Contrary to intuition, the speed of light (properly defined) decreases as the black hole is approached...If the photon, the 'particle' of light, is thought of as behaving like a massive object, it would indeed be accelerated to higher speeds as it falls toward a black hole. However, the photon has no mass and so behaves in a manner that is not intuitively obvious."
http://www.physlink.com/Education/AskExperts/ae13.cfm
"Einstein first discovered the gravitational time dilation in 1911, on the basis of his equivalence principle. From the time dilation, he immediately deduced the slow-down and deflection of light in a gravitational field. His 1911 result for the reduction of the speed of light was in error by a factor of 2, but he corrected this a few years later, in his theory of General Relativity."
https://arxiv.org/ftp/arxiv/papers/1102/1102.2870.pdf
"Thus, as φ becomes increasingly negative (i.e., as the magnitude of the potential increases), the radial "speed of light" c_r defined in terms of the Schwarzschild parameters t and r is reduced to less than the nominal value of c."
https://www.mathpages.com/rr/s6-01/6-01.htm
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All Einsteinians know, and some explicitly admit, that the opposite is true - the speed of light INCREASES as light falls in a gravitational field:
James Hartle, Gravity: An Introduction to Einstein's General Relativity, p. 113: "If we accept the equivalence principle, we must also accept that light falls in a gravitational field with the same acceleration as material bodies."
https://www.amazon.com/Gravity-Introduction-Einsteins-General-Relativity/dp/0805386629
Paul A. Tipler, Ralph A. Llewellyn, Modern Physics: "But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2."
http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.pdf