I still don't get how it's supposed to be more efficient than setting up prefabricated moulds, hanging the conduits and placing the rebar, then pouring concrete from trucks... Yes, the moulds have to be taken off after waiting for the walls to cure enough to support themselves, but typically mass-construction of even identical buildings will see staggered stages including rough ground prep, survey for foundation positioning and marking that, installing the in-ground utilities/services/piping, pouring the foundation and slab, finishing off the stub-ups through the slab, building the load-bearing walls, building the roof, roughing-in the interior wall studs, putting in electrical/plumbing/etc, then finishing the interior walls and exterior of the building.
That process can be staggered across several buildings so that the time to build ten buildings in-tandem isn't a lot worse than if two buildings were built, each start-to-finish before the next. I don't see how using a 3d printer really helps. 3d printers are great for prototyping and small-batch work, but it's almost always more cost effective to build special-purpose to make things in volume if the volume is enough to pay for the machines. 3d printing would work great at home or in a boutique shop, but I don't see it being a major factory process for finished goods.