Sometimes it is best to see a theologian in action to determine their view and attitude about inerrancy. There is a classical error in most of our Bibles in Matthew 27:9 where Matthew means to quote Zechariah 11:13 concerning the 'thirty pieces of silver' but it says ‘Jeremiah’. I have glanced at a few modern explanations about this and it seems sufficiently resolved under several theories, one of which the original did not have the prophets name and the error creped in by a copyist mistake. The Syriac version, for example reads only, It was spoken by the prophet, not naming any.
Alright but how would Calvin and Luther approach this when maybe this kind of explanation was not readily available?
Here is what Calvin said:
How the name of Jeremiah crept in, I confess that I do not know nor do I give myself much trouble to inquire. The passage itself plainly shows that the name of Jeremiah has been put down by mistake, instead of Zechariah, ( 11:13 ;) for in Jeremiah we find nothing of this sort, nor any thing that even approaches to it.Calvin's Commentaries, Vol. 33: Matthew, Mark and Luke
This is what Luther said:
Jerome brings up the question why the evangelist Matthew cited this testimony as being from Jeremiah when it never appears in Jeremiah but in this prophet, Zechariah. Briefly, I have this to answer: the evangelists do not generally cite testimonies from the prophets word for word. They merely bring out the sense. This is what Matthew also does in the passage we mentioned above in chapter 9:9, where the prophet said: “Rejoice greatly, O daughter of Zion. Shout aloud, O daughter of Jerusalem.” Matthew cites this as follows (Matt. 21:5): “As it is written, tell the daughter of Zion, Behold, your King is coming to you, etc.” Here, clearly, the words are different. Yet nothing of the sense has been changed. Then, too, Matthew added (Matt. 27:9) “by the children of Israel,” which does not occur in the prophet This Matthew obviously did to explain that buying and selling and to warn that the children of Isarel were responsible for it. As to the fact that He cites the testimony as coming from Jeremiah, I have nothing else to respond than this common answer, that the prophet perhaps had two names or that in the custom of other evangelists, too, Matthew was quoting generally, without any concern for the name of the prophet. Augustine (q. v.) discusses this passage carefully, would not readily believe that the names of the books of the prophets were exchanged because of changed tittles. Then, too, there undoubtedly were with Matthew saintly and learned men, filled with the Spirit, who advised him that the Scripture which he cited was in Zechariah, not in Jeremiah. Admonished by their advice, he could have corrected that slight error, had he wished or had he thought it important. But there is no reason for us to bother ourselves with these and similar difficulties. After all, the life and sum of our faith do not lie in them. Those people who labor over nonessential matters of this sort are more than mad. Yet this is one thing which the prophets of our day try to do when they read Scriptures for the purpose of searching out texts like this which they can use as the handle and material of debate and controversy. In the meantime, they neglect the lifeblood of religion, when they ought to be performing this one duty especially—teaching a ruling Christ, This is something all the apostles do with unanimous agreement.
Conclusion: The reformers certainly believed in the inerrancy of scripture (as they usually make effort to resolve apparent contradictions) but they did not feel the need to resolve every little minute detail and fact and actually did not seem overly bothered if a small fact, unrelated to anything, was wrong. They seemed less obsessed about small unrelated facts compared to us. They did not seem to put their hands over the ears like Edward Much's famous painting 'scream' and think, ‘If we allow one mistake then who is to say that all is not a mistake, Oh boy, worry me, the sky is falling, what shall we ever do?’ I am not saying there are any mistakes in the original text, but I do wonder at times whether it matters. I think we could learn from the attitude of the reformers a bit on this one.