Not all ABS Bibles were of the 1851 corruption, but it was clearly inferior to any English printed Bible from London, Cambridge or Oxford.

The American Bibles of 1830-1850 was probably more or less following Oxford, so this is not an issue. The American Bible of the 1850s were the most corrupt. The edition which came out in 1860 onwards was less corrupt.

If the American "modernisations" were so prevalent, why is it that the KJB using Americans generally have used Oxfords and Cambridges until recently, and why was even the popular Thomas Nelson edition (e.g. in the 1980s) about halfway between being an Oxford and a Cambridge, rather than anything like the updating all that so called archaic language like the American revision had done?

In other words, it appears that somewhere long ago the modernised American editions fell out of any kind of prevalence.

But we know that millions have used both impure and also counterfeit KJBs. God was still able to move and work besides this. Millions of Pure Cambridge Editions have been printed too. I am not suggesting that someone in 1850 did not have the Word of God because the Pure Cambridge Edition did not exist. Clearly, God has providentially worked things out so that people might eventually come to the final pure, and that required finalising the purification first.