Yes - this is the module that translates the human's controls into the actions by the car to make them do what the human wants.
Next week I will hit the 1-year mark with my 2016 Volt and the only thing that was an issue was that I needed to have the HMI replaced, and a few others on the Volt forum reported the same. Shortly after I had mine replaced they put out a service bulletin that alerted dealers to either get a software update (I think that was the first step) or HMI replacement (if update didn't help) if the owner reported issues such as the following. I had the first two symptoms as the screen would go blank, and the volume knob would not work but the volume buttons on the steering wheel would work fine.
• Random Infotainment system resets while driving, screen temporarily goes blank and then returns after approximately 5 seconds
• The radio volume knob (non Cadillac) or slider bar (Cadillac) will not function
• The HVAC controls function but will not show changes on the display
So based on the list that you found in Etis, the Fusion Hybrid apparently has an 'HMI 4' to manage the human's inputs on the touchscreen etc into actions by the car.