Hey, i'm not sure this is the right sub for this question and if this not right feel free to delete it and sendnme pver to the correct subreddit.
So, anyways, could it be possible that books can falsify history? Today nobody denies there was a man called Napoleon and we have ton of resources about him. But nobody actually saw the man or was present in that time to witness the changes he made. We luckily have ton of resources about him and nobody can deny there was a man called Napoleon that changed the course of history.
But let's take an old manuscript, which makes a statement about a guy who changed the course of history but nobody can remember him. Why should I, believe that old manuscript who states that guy is a true document from that time, and if the opposite, just some made-up story that we think is real and believe that there actually was this Napoleon-like dude who changed history?
Given your circumstance, you should look for other sources that mention or involve your person in question, as just one historical mention isn't sufficient information to rule out whether or not that person changed he course of history or even existed.
It should be noted that "false history" or "falsifying history" has been a common trend amongst many of history's historians, as things like historical bias exist. in many cases, we have no true access to what ACTUALLY happened, and thus we're forced to make sense of things by drawing from various sources, contemporary or not, use logic and reason, and use new found information to reflect on the observations of earlier historians.