Possible alternate approach
Have the same gantry, but instead of liquid concrete, have it take a feed of CMUs, and make a stack-block, then drop rebar down the holes, then fill holes with an expanding polymer foam to both consolidate structure and insulate, then spray the outside.
A robot arm to handle CMU's (feed it two types, hollow and solid), an automated chop saw to slice hollow to length for openings, etc, and a feed/cut rebar feeder all seems less complex and faster than "3-D printing" the concrete...faster too, A LOT faster.
I'm thinking a huge-ass Delta-robot (like a pick/place) with support legs on adjustable height struts on little tracked units, but handling blocks, at the speeds of industrial robots (1-2m/s) one could easily get 5-10 blocks a minute...or given a 12x8x6" block size, about 15-30 feet of 10ft high wall per hour.
Better yet, since this already developed the nozzle tech, have it mortar the blocks as well, (easier, patterned nozzle, squirt, set, repeat).
Robot then follows wall path.
Hell, make it super easy and just cast the blocks with interlocking features to ease setting, and use an industrial adhesive to glue them together. Once wall is up, robot simultaneously drops a regard down each hole, and fills hole with foam. (Or for really fast fill, a nozzle that shoots foam "peanuts" and a spray of expanding foam simultaneously down the hole)
Given that its super easy to have a robot position/hold a block and have a drop saw cut it, and super easy for it to move/position known size items FAST, this printing one seems almost like an academic excercise.
