What does "more engagement" look like? What behaviors denote "more engagement"?
Once you talk to 10-20 curators you should have a solid understanding of what "more engagement" means to them.
From there brainstorm possible solutions that will effect that.
Rank your solutions on a graph with Bold - Not Bold on one axis, and Likely to Solve - Unlikely to Solve on the other.
Create experiments starting with the most bold and most likely to solve idea.
The boldest, most likely to solve idea that subscribers and curators are willing use will probably be innovative and better define your UVP.
Ask your curators if they had any specific ideas for engagement and see what the subscribers think about that.
You've got to be your product's non-technical founder, and coordinate with your users and customers to build what they want.
Idea #2: Go talk to your curators, or whoever you think will be your curators.
Your questions above point to the fact you are trying to solve your problem (how to get customers), rather than your customers problems.