Hi Oriol,
You are correct. If you use the MATLAB filter wizard, it calls the following two functions to set the half band filters:
mathworks_tools/setrxhb9361.m at master · analogdevicesinc/mathworks_tools · GitHub
mathworks_tools/settxhb9361.m at master · analogdevicesinc/mathworks_tools · GitHub
So basically, the wizard sets it for you. You cannot specify it yourself.
Best,
Di