Did the Cockcroft‐Walton experiment really confirm Einstein's ΔE = Δmc² first of all?

The original aim of Cockcroft and Walton's experiment was to disintegrate Li⁷ with fast protons yielding alpha particles. Energy of 17.2 MeV was emitted. This experiment is regarded as the first confirmation of ΔE = Δmc². The theoretical re-analysis of data as given by Cockcroft in his Nobel Lecture justifies only splitting of Li⁷ by fast protons and is not consistent with ΔE = Δmc². The values of the masses of proton, Li⁷, and alpha particle have varied significantly due to improvements in the precision of instruments. If the values of reactants (¹H = 1.0072 u, ⁷Li = 7.010 4 u) and products (2 × ⁴He = 8.002 2 u) are taken in account as existed at the time of Cockcroft's experiments, then percentage difference from ΔE = Δmc² is 16.594. Soon after this, Bainbridge improved the value of the mass of Li⁷ at 7.0130 amu. Then the percentage deviation from ΔE = Δmc² decreased to 2.491. If the current values of the masses of reactants (¹H = 1.0072764 u, ⁷Li = 7.01600455 u) and products (2 × ⁴He = 8.0030122 u) are taken, then the percentage difference turns out to be 9.768. In a nutshell, it is concluded that such a significant experiment which is regarded as first confirmation of ΔE = Δmc², be repeated with very precise instruments, eliminating all possible sources of errors, then results be compared with ΔE = Δmc². Cockcroft and Walton's experiment has not been repeated by scientists, which increases the significance of the repetition. It is a basic principle of science that no conclusions can be drawn on the basis of a single observation. Results are widely accepted if repeatable.