But the bottom line is that introspection is not necessarily reliable.
The existence of cognitive dissonance suggested in your citation is in no way analogous to "our own explanations about ourselves and our behaviour are mostly lies, fabrications, hallucinations, faulty re-memorization, post hoc reasoning" and in fact supports the opposite.
In the morning when we wake up, we are "booting" up the memories the brain finds and we believe that we have persisted through time, from yesterday to today, yet we are absolutely sure that is a lie: just look at an Alzheimer patient.
We are feeling this self as if it's somewhere above the neck and we feel like this self is looking at the world and sees "out there", yet we are absolutely sure that is a lie: our senses are being overflown by inputs and the brain filters them, shapes a model of the world, and presents that model to the internal model of itself, which gets so immersed into model of the world that starts to believe the model is indeed the world, until the first bistable image [1] breaks the model down.
[1] https://www.researchgate.net/profile/Amanda-Parker-14/public...
Even if you accept classic theory (e.g. hemispheric localization and the homunculus) which most experts don't all this suggests is that the brain tries to make sense of the information it has and in sparse environments it fills in.
How does this make our behavior "mostly lies, fabrications, hallucinations, faulty re-memorization, post hoc reasoning" as most humans don't have a severed corpus callosum.
The discussion starts with:
"In a healthy human brain, these divergent hemispheric tendencies complement each other and create a balanced and flexible reasoning system. Working in unison, the left and right hemispheres can create inferences that have explanatory power and both internal and external consistency."