This one is really interesting. Personally, I think I'm more aligned with the first definition, of someone who creates tooling and capabilities to support communities and the community builders, vs calling a community builder a Community Engineer (though I definitely get where you're coming from, and can understand the merit of what you've proposed).

I think there is a big void when it comes to development/engineering resources that community teams are allocated, and the selfish part of me wants Community Engineer to fill that particular void.