I'm not defending them, but just a few thoughts...
All frame sliders on bike's with a full fairing require that a hole be cut through the fairing, it's that "no two objects can occupy the same space" rule... Most all frame sliders (even high quality ones; Cycle Cat, etc.) do use the engine mount bolt (it's the most ridgid part of any frame)... Only the bike manufacturer (Honda in this case) can control how close the engine mount bolt is to the fairing bracket, not an aftermarket company. As for hardened vs. unhardened bolts there are volumes of engineering data regarding life-cycle fatigue and impact failures, exceeding elastic yields, etc... To greatly generalize, hardness = brittleness... The harder the steel is, the more brittle it becomes and more prone to breaking (breaking may actually be a benefit in a design such as this and be intentional)... The Titanic wouldn't have sunk when it hit that iceberg if it didn't have so much carbon in it's chemistry (high carbon = high hardness {again, generally speaking})... Again, I'm not defending the maker of these frame sliders as they do sound marginal from what you described, but I'd be interested in seeing your design for a frame slider system, that doesn't use the engine mounts (strongest location), and doesn't extend pass the fairing (what you are trying to protect)... It would be an interesting design to say the least.