Depending on how things were weighted would really make a big difference. Especially since a lot of these theories make use of (aggregates of) proxies to measure what they really care about as the data you care about is long lost to history.
WRT overfitting, it would not be too hard to measure the error on a holdout set. Turchin et al. essentially used China as their holdout set.
Nobel Laureate in Econ Elinor Ostrom describes how in the real world we have a variety of formal And informal governance structures (that do negotiated decision making, monitoring, conflict resolution, punishments, etc.) to allow both local and global optima. From an info-processing view you know locally what’s best for you, but you need a way of aligning local decisions to reach global optima. Because this is very complex and fuzzy we humans have nested overlapping norms and institutions to govern behavior while allowing freedom and flexibility.
To see culture from a more CS perspective look up papers on “cultural evolution” and cooperation. The books / blog by evolutionary biologist / historian Peter Turchin “War and Peace and War” and “Super Cooperators”. Behavioral research on altruism and costly punishment in repeated prisoners dilemma games also shows the importance and impact of culture.
In this interpretation a “good” culture is one that has more solidarity & honor than back-stabbing & free riding. From a purely economic perspective it creates greater overall welfare and trust.
From an evolutionary perspective “more fit” cultures replace less fit ones, especially via invasion or general external pressure. When there is a lack of sustained external threat to incentivize collective action, cultures often devolve into decadence, back-stabbing and mistrust like Mafioso Sicily.
High social cohesion isn’t necessarily morally “good” though. Catholic Spain was super cohesive when kicking out the Moors. It propelled them into a golden age, but it also turned them into genocidal intolerant maniacs.
A good example of a strongly cohesive culture today is South Korea. They are always under threat of invasion from many sides, so they built a culture of super strong cohesion, hard work, etc.