Right, so I figured I should build the CPP from the git project too, which I had not before. But it still doesn't work.
It doesn't build a civ5mod though, it builds a mod folder. The strange thing is, sometimes when I access those mods, I find a second folder in MODS\ with the version number for CP and CBP right beside the Mods\Community Patch and Mods\Community Balance Patch I myself put there. And sometimes that doesn't happen.
Either way it softlocks when loading the mod.
Humourous note, if you put the Object File library that gets built along with the dll into the mod folder, just put it there, don't actually build it into the mod, Civ V itself crashes while loading its main screen.
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Oh also, I set the linker to switch /LTCG because the notices at the bottom say it is doing that anyway when it finds it can't proceed, so that's slashing the link-time in half. Obviously that isn't helping me, but seems like it could be profitable for the vcxproj on git to be set to that. The claims that ltcg isn't compatible with a precompiled header are apparently not valid - not that it's a matter of choice since, as the linker says, it is doing LTCG anyway.