XComGameStateContext_StrategyGameRule.CleanupProxyVIPs ensures that the death and injured status of VIPs are copied across to the corresponding Avenger units, but that's it. One important piece of information that's missing is whether the unit actually left the mission successfully, such as via an evac.
Other things to consider are kill counts, particularly if you have soldier VIPs that can shoot on missions. But perhaps they don't use proxies.
I see this issue mentioned in comments in Highlander's code, though not sure which PR added it. In any case, please add docs so this issue can be closed.
XComGameStateContext_StrategyGameRule.CleanupProxyVIPs
ensures that the death and injured status of VIPs are copied across to the corresponding Avenger units, but that's it. One important piece of information that's missing is whether the unit actually left the mission successfully, such as via an evac.Other things to consider are kill counts, particularly if you have soldier VIPs that can shoot on missions. But perhaps they don't use proxies.