It seems unlikely that this really occurred to nobody at all. It seems so obvious. So I'd imagine that this was brought up at various points but others would rationalize it away somehow saying things like "God wouldn't let that happen" or "a good person wouldn't lie just to stop pain" or coming up with ways of telling when confessions are fake based probably on some manner of superstition. Or if assuaging concerns about a specific person's confession bringing up points against their character.

But what I want to know is whether any sources referencing discourse or any writings or essays discuss the concern that torture could cause false confessions and especially anything where it shows others responding to those concerns with rationalizations in favor of torture.