Hmm, I think the easiest thing to do with that is to do the engagement ourselves
I agree. The problem is really the time here: I do tons of other things for the community I belong, on top of a very time-consuming job.
We currently try to motivate our entire crew of curators to leave comments in the posts they curate, and we are planning to make some noise about our "honour members" (i.e. a honourary title given to dedicated community members who are exemplary in terms of engagement) in a few days. Any mean (some gamification here) is good to fight on this front! I just hope this will go somewhere...
As long as someone believes in it, it will. Honour members sounds fun. I would do my best just to get the Queen Of Engagement 2020 title. :p