The airlock scenario has been discussed on here for years, Haydn came up with the high level add on, that should & did detect the airlocks in my case recently, but he had virtually no take up on the high level add on.
"Engine Saver" is just a trade name based on what it can do, if you buy Shell fuel do you expect to get a tank full of shells? or if if you buy "Star Drops" detergent do you expect it to be full of stars?
It's called a low coolant alarm, it detects low coolant, it has it's limitations as does anything, but if the coolant drops it picks it up. I would always recommend fitting the LCA & Mason alarm as a minimum, as that covers most eventualities, BUT still not all, that would be virtually impossible/cost prohibitive.
You can't polish a turd - but you can roll it in glitter.