Being interested in CoP won't be the only reason for people to submit to SCooP, but they also want to improve their publication record. I think that this year's review helped to increase the quality of the submissions, and next year we should proudly announce this in the CfP: that there will be reviews, and who will be on the programme committee.

I've never understood whether CoPs are a CS or a sociology topic. What are the communities interested in CoPs?

I suppose it's mainly among sociologists, so SCooP should appeal to them more. In any case, SCooP can target all scientists, not just computer scientists.

In general, I think you (Christine) should identify some professors from all fields interested in CoPs. Contacting them and their communities could be a starting point to reach a broader audience.