I am researching this as well. I am just getting a small organization up and running with the goal of migrating to a better Corteza environment later. I hav ebeen struggling with workflows, even having someone paid to make the workflows work for me. Also I ran into lots of problems with the importer, which makes me wonder if it would be easier to write my own sql import. (I believe the importer does some record checking and when you put it against several thousand rows it craps out.
Have you tried backing up with a docker commit / backup of the server/db image and restoring that way? It was on my list of things to attempt.