Featured What Greek text did Jerome use?

Good, and I thank you for that reference. My point in relation to the discussion, however, is that in December 2020 I could not have known that you would provide quotations from a leading authority concerning the Latin New Testament. I could only respond to what you had already posted.

Yet, an answer to the question in the OP does not depend on my perspective of the KJV. You admit that you view those quotes you gave as "generalized" and "claims". I was hoping/asking for recent, detailed, and/or specific (which Houghton fits quite nicely).

 

Looking at what I can see of Houghton's work on Google Books, I found the following interesting on this topic.

Speaking of differences in Jerome's translation of the Gospels and the Old Latin, Houghton writes, "Some of the differences in Jerome's version derive from the Greek text on which he relied. It has often been observed that the Vulgate moves away from the so-called 'Western' text towards a form closer to the later standard (koine or Byzantine text), although attempts at more detailed classification tend to founder."

This is accompanied by footnote 47, in which he references some other works and then states, "It was once thought that Jerome's Greek text was similar to Codices Sinaiticus and Vaticanus, but this is no longer the case."

The Latin New Testament: A Guide to Its Early History, Texts, and Manuscripts, by H. A. G. Houghton (Oxford University Press, 2016, pp. 33-34)