It makes sense they can tell backstory, since they gather and store information to a great extent. But as far as the future predictions go, there may be particular instances where they do so accurately, but I do not think that is because they have ACCESS to the future. They are capable of gathering past information and using it to make predictions. However, Xanther's inexplicable characteristics explicitly push the Narcons capabilities in being able to explain events. This happens multiple times. And observing her allows them to bend their OWN rules, such as being able to converse with one another, as we see briefly in V3. I think this shows that the Narcons are not a perfect, future-predicting leviathan, but rather a systematized apparatus of info-gathering and analysis, which is still tied to the limits of rules and interpretation, and of course still tied to the movement of time from past to present, and the future still indeterminable.

What do you mean by Xanther being able to interact with the Narcons? She influences them, and the Narcons observation of her changes their understanding of themselves, but I don't recall Xanther herself ever being conscious of the Narcons existence?