reduction in lifespan of 7 to 15 years (Kolassa, Iris – Tatjana. "Biological memory of childhood maltreatment – current knowledge and recommendations for future research"

Given that the abstract doesn't say so, that's very likely to be a misreading. My guess is that they report correlations but haven't ruled out genetic effects. The same is true for the other studies you link for harm, they also seem to talk about correlations.

Neglectedness

You don't talk about the amount of government money that's invested into the cause.

Given that ‘’three quarters of substantiated cases of physical abuse of children have occurred within the context of physical punishment’’, (see tractability section) assuming that a ban on corporal punishment towards children could be enforced with just 10% compliance worldwide, we could save a minimum of 10% * ¾ * 51800000 QALY’s per year = 3885000 QALY’s per year.

No, there no reason that a 10% compliance rate would be equally distributed among different risk groups. The parents who make a deliberate conscious choice to use corporal punishment are less likely to go into stronger abuse than parents who react because they can't manage their emotions well. The parents who act because of deliberate conscious decisions are more likely to comply.