Maybe this isn't the right fit, but a company I'm invested in and have advised since its inception is https://app.getriver.io/home

It's built around managing a community, from the perspective of the community manager or head of community. It harnesses the power of hosts, the people who actually make the events happen and captures the free energy in the system of human to human community.

I actually think for your use case it would be perfect. In each town you can crowd source (or directly invite the facebook group admins as hosts) hosts to create events and then run them. The platform started from creating and scaling the All-In Podcast community and now have worked with Tim Ferris, Blueprint/Don't Die, and next week all the events for Utah Tech Week https://app.getriver.io/utahtechweek