One would need to find writings of those who compiled this confession of faith that make that claim to establish a KJVO position from this. That they call a translation the Scriptures does not correlate to them meaning the translations are inspired.
KJV-only advocates are trying to read something into the Westminster Confession of Faith about Bible translations that it does not state.
There is clear historical evidence that some members of the Westminster Assembly considered the KJV to have some errors [both errors in printing and errors in translation] and to need revision since they were involved in an effort to revise it in the 1650's.
A bill for revising the English translation of the Scriptures in the 1650’s passed by Parliament would show that Bible translations were not considered to be inspired or perfect by the Westminster Assembly since some of its members are named as involved in an effort to revise it.
John Stoughton cited this bill as stating: “it is our duty to endeavour to have the Bible translated in all places as accurately and as perfectly agreeing with the original Hebrew and Greek as we can attain unto” (
Ecclesiastical History of England, II, p. 545). From a draft of a bill for revising the English translation, John Stoughton listed the following men who were to “search and observe wherein the last translation appears to be wronged by the Prelates, or printers, or others”: “John Owen, Ralph Cudworth, Mr. Jenkins, William Greenhill, Samuel Slater, William Cowper, Henry Jessey, Ralph Venninge, and John Row” (
Ibid.). Stoughton cited the bill as appointing Dr. Thomas Goodwin, Dr. [Anthony] Tuckney, and Mr. Joseph Caryl as supervisors of the revision (p. 545). Ira Price observed that “the reasons that lay back of the bill were in part errors, mainly printers’, and some in translation, and also the so-called prelatical language of the version” (
Ancestry, p. 280). Henry Barker noted that “the errors of the Authorized Version, through careless editing and proof-reading, but still more what was called its ‘mistranslations’ and its ‘prelatic language’ contributed toward the movement” (
English Bible, p. 187). H. W. Hoare wrote: “In part they were influenced by the fact that many blunders had already come to light in the printing, and that the new edition was accused in certain quarters both of numerous mistranslations and also of “speaking the prelatic language’” (
Evolution, p. 275). John Eadie pointed out that the report of 14 changes made by prelates became part of the preamble of a bill in Parliament around 1657 (
English Bible, II, p. 272). John Eadie cited that preamble as noting that “the like testimony of these prelates” making those changes was “given by some other ancient and godly preachers also, who lived in those times” (
Ibid.). Eadie also reported the preamble affirmed that “some appearance hereof may yet be seen in part of that very copy of these translators” (
Ibid.).
The Calender of State Papers, Domestic Series, 1652-1653 as edited by Mary Green noted: “Statement that Dr. [Thomas] Hill declared in his sermon, and has since published, that when the Bible had been translated by the translators appointed, the New Testament was looked over by some prelates he could name, to bring it to speak prelatical language, and that he was informed by a great observer, that in 14 places, whereof he instanced five or six, it was corrupted by them. The like testimony was given by some other ancient and godly preachers who lived in those times, and some appearance hereof may yet be seen in a part of that very copy of those translations” (p. 73). In his 1648 sermon, Thomas Hill (c1602-1653), a member of the Westminster Assembly, had stated: “I have it from certain hands, such as lived in those times, that when the Bible had been translated by the translators appointed, the New Testament was looked over by some of the great Prelates, (men I could name some of their persons) to bring it to speak
prelatical language, and they did alter fourteen places in the New Testament to make them speak the language of the Church of England” (
Six Sermons, p. 24; see also Currie,
Jus Populi Divinum, pp. 37-38, Eadie,
English Bible, II, p. 272, and Bridges,
Patronage in the Church of Scotland, p. 6). This historical evidence would demonstrate that members of the Westminster Assembly considered the KJV to have some errors including some in translation, to have some prelatical language indicating episcopal bias, and to need revision.