This is one absurdity after another! Many KJV Bibles do not even have a study guide, nor was the KJV the first Prot. Bible, and most modern Prot Bibles do not even use the same family of MSS, and can be more different in their renderings than the RC DRB is within the 66 books, which is overall very similar. Compare the Message or Good New Bible with the KJV.
The Douay–Rheims Bible achieved little currency, even among English-speaking Catholics, until it was substantially revised between 1749 and 1752 by Richard Challoner, an English bishop, formally appointed to the deserted see of Debra. Challoner's revisions borrowed heavily from the King James Version (being a convert from Protestantism to Catholicism and thus familiar with its style) - he Rheims New Testament
And the Rheims New Testament is seen as having a little influence on the KJV.
And as Prot Bibles can differ due to translation and the school that did it, they can sometimes contradict what the KJV says, and could even agree with a Catholic rendering of a text.
Finally, the CCC is not like a Bible study guide, as it does not go thru the Bible and comment on chapters and verses, but simply quotes or references a relatively small portion of it.
And which does not even necessarily mean that this is an indisputable interpretation of it, as very very few texts of Scripture have been infallibly defined. In fact RCs have a great deal of liberty to interpret Scripture in seeking to support Rome, which they too often creatively attempt to do.
The CCC is a reference work for teachers of RC doctrine, which does not even rest upon the weight of Scriptural warrant for its veracity, while a Bible study guide would be like that contained in NAB study Bibles.
Once again your argumentation provides more evidence why one should not be a RC.