Is biblical inerrancy just for the original version? The substance of this question is whether our English (or French, or German, or Spanish, etc.) translations may be considered inerrant? The short answer is: yes, we may regard translations as inerrant insofar as they accurately reflect the original text (autographa).
First, let us define our terms. The historic Christian church has always regarded Scripture as the inspired, infallible Word of God. In the Nicene-Constantinoplitan Creed (AD 381), the church universal confesses that the “Holy Spirit… spoke by the prophets.” We regularly see the fathers of the church describing Scripture as infallible, i.e., incapable of error. When we say that Scripture is inspired, we mean “breathed out by God” (θεόπνευστος; 2 Tim. 3:16). It means that the Prophets and Apostles wrote as they were “carried along” by the Holy Spirit (2 Pet. 1:21).
This is what the Westminster Divines wrote and what the Reformed churches confess regarding the importance of both the original texts and translations:
The Old Testament in Hebrew (which was the native language of the people of God of old), and the New Testament in Greek (which, at the time of the writing of it, was most generally known to the nations), being immediately inspired by God, and, by his singular care and providence, kept pure in all ages, are therefore authentical; so as, in all controversies of religion, the church is finally to appeal unto them. But, because these original tongues are not known to all the people of God, who have right unto, and interest in the Scriptures, and are commanded, in the fear of God, to read and search them, therefore they are to be translated into the vulgar language of every nation unto which they come, that, the Word of God dwelling plentifully in all, they may worship him in an acceptable manner; and, through patience and comfort of the Scriptures, may have hope (WCF 1.8).
The original texts, the autographs, the Hebrew, Aramaic (parts of the Old Testament are in Aramaic), and Greek texts given by the Holy Spirit, through the Prophets and Apostles, are inspired, infallible, and inerrant.
That last adjective, inerrant, has been a source of controversy since the late nineteenth century when orthodox Christians of various traditions began using it to say that not only is Scripture infallible but it is actually without error. We adopted this language to respond to the rationalist (i.e., those who put human reason above divine revelation) critics of Scripture. For more on the inerrancy of Scripture, see these resources.
The final authority for Christian doctrine and the Christian life is the Word of God in the original languages.
The final authority for Christian doctrine and the Christian life is, as the Westminster Divines wrote, the Word of God in the original languages. Textual criticism is the business of deciding, when there is a question, what the original text was, i.e., which is the most likely reading or text in a particular instance. Biblical scholars have always practiced textual criticism: the ancient fathers did it, the Renaissance scholars advanced the practice, as did the Protestant Reformers. The questions grew, however, in the late nineteenth century when scholars found a large cache of ancient texts in Egypt. It is important to note, however, that none of the various readings substantially changes biblical teaching. Many of them, particularly in the New Testament, are obvious later emendations by copyists who were seeking to clarify something that they found troubling. Others were marginal notes that came to be copied into the body of the text. We have a marvelous treasury of ancient texts of the the Scriptures, and the Christian may have a high degree of confidence that within those texts we have the autographs, i.e., the text of Scripture as given by the Spirit through the Prophets and Apostles. For more on this see these resources.
Because it is Scripture in the original languages that norms our faith and practice, it is essential that our pastors and teachers receive a genuine education in the original languages. This is why we should expect them to continue learn and progress in their knowledge and use of the original languages in pastoral ministry. For centuries before the Renaissance and Reformation, most the ministers in the Western church lost the ability to read the Scriptures in the original languages. Indeed, to find an illiterate priest (one who could not read at all) was not unknown. In the Greek church, of course, they could at least read the New Testament but it was not until the Renaissance that the knowledge of Hebrew and Greek began to return more widely and to be taught again in the universities, where pastors were educated. The Reformed churches understood and appreciated the value of the knowledge of the original languages and expected the pastors to learn and use them.