The concept called "unattended engine room" means that no one is watching, in the engine room. To achieve this "savings" of monitoring, regulations require an endless set of sensors, alarms and some other devices, precisely to avoid continuous monitoring of the human eye. And, really, an engine room "unattended" is more secure than a "normal". If the aim is to replace the presence of a person within the engine room by another person, outside, occasionally looking for a monitor, I do not think that contributes nothing to the safety of the ship. Perhaps the Captain "dazzle" the passengers with their full set of TV monitors, but little else can be done with them. I assume further that such monitors can not cover eliminate the placement of sensors and alarms required by SOLAS or the Classification Society.
But all the above is just my humble opinion.