Although checking the facts in your text is beyond the translator’s remit, hiring a linguist who has a certain level of expertise in your particular field could save you from the embarrassment of oversights.
Of course, a translator will focus on the language first; the content is down to you and, if there are mistakes in the source document, the translator cannot be expected to spot them all, if any. It is your responsibility to ensure that the text is accurate and ready for publication. But we’re all human and, despite your diligence, translators often have queries: it may be a small technical point, such as an unclear sentence or a missing word, something that doesn’t quite make sense or is ambiguous, or there is a fact that your translator knows to be wrong – that is, if they are conversant with your subject.
While working on an art book a few months ago, I spotted a couple of inaccuracies. The first one was that J. M. W. Turner did not die in 1844 but in 1851. Did the author confuse the date with Rain, Steam and Speed, a painting mentioned elsewhere in the book and which was first exhibited in 1844? While this mistake would most likely have escaped a non-art specialist, it did not escape the translator who wrote her MA dissertation on Turner.
The second issue was an inconsistency that highlighted another date error: in the introduction, it was mentioned that abstraction started around 1912. In a subsequent chapter, it stated that the first abstract painting had been made by Kandinsky around 1913. Although I could not remember the exact date, I knew which painting this referred to, so it only took me seconds to find it online and check its date: 1910. I left the date of “around 1912” in the introduction because you could argue that abstraction did not happen overnight, but edited the text where it specifically mentioned Kandinsky’s watercolour and made the publisher aware of this change and of the date stated in the introduction, which they might wish to change also.
Sadly the French book was already published by the time I worked on this assignment, but the British edition at least has benefited from the sometimes unexpected value of working with a specialist translator.