I also got a similar point, I have my user design GDS integrated but got stuck in the next stages.
1. I have an issue with the precheck because a use spice netlist can't be specified unless the managment area netlist is also spice - and that doesn't currenty exists https://github.com/efabless/open_mpw_precheck/issues/19
2. The 'make ship' command fails for me on the mgmt_core gds even though I haven't touched that
So there's a couple of kinks that need to be ironed out, but all in all, pretty close I think