Indeed, pronation is a natural healthy and beneficial motion.
yes, there is no definition and understanding as to what defines normal and what constitutes overpronation.
certainly, plenty of people overpronate and get no issues.
certainly, other overpronate a small degree and experience lots of problems.
yes, multiple factors of this condition. https://podiatry-portal.com/is-overpronation-a-problem-or-not/