My professional opinion? ...i'm 100% sure what you did is less safe than factory and by a good margin. Its all about your risk tolerance/aversion. We all run around with a fair amount of loose things in our vans, any one of which can kill you as it flies around in an accident. I like to mitigate risk and I am not someone who would bolt a reclining seat through the floor with fender washers because I can do some very simple FEA and know that its unsafe to do so. SImilarly I both belt and LATCH my kids car seats, because I did the analysis on the latch bars and with my kids weight + their car seat weight, they exceed the ultimate tensile strength of the latch bars with accelerations found in common collisions. The bars were designed for around a 60lb kid. I believe they forgot they needed to factor the car seat weight. At 100lbs of kid+seat....you get it.
Anyway, where you bolted that is appreciably more likely to fail in an accident than the factory points, IMHO. Will it? Depends on the accident (severity, angle, passenger weight, any number of other factors). But then you can die in a factory seat too soooo.........To each their own. I was only saying I would have personally taken the time to mount it differently.
It looks like a good bit of quality work and craftsmanship. I just disagree with some details. To each their/our own