The diagrams provided are VERY elusive. I could not get a pair of vzm31-sn switches to work in 3way. The wiring was easy but the configuration of parameters made little sense. Reading these help pages reveals no-body has asked about this issue in the past 5 years. So either I don’t get it or the drawings are outdated. Well I found I did NOT need to use a pair of these switches to get the simple functionality I desire. I simply used one of the smart switches and one aux switch. No configuration needed, it just worked and zwave in Home Assistant is also working great.
Just needed to set up bindings between the two so they controlled each other. This is for the fan canopy but the idea is the same