Ok, so if you don't understand it, then I wont either.

This is pretty much like changing brake pads or doing other safety related maintenance to your car. If you are not expert (I mean like educated car mechanic specialist), then you should not do it. Or would you do it anyway? I bet you are not calling your insurer to be sure can you change your brake pads or wheels by yourself, what if brakes fail or wheel drop of at high speeds..
Common sense is usually what it takes, it is same here. Little engineering skills will also help.
When you install that isofix anchor in, you can inspect that installation and think it through and then decide is it safe for use or not. That is what I did here and I decided that it is safe for use.
So I'm very much in my senses from the beginning.
I'm happy to receive advises and tips, but I don't need any guesses with no or very little knowledge behind them (like why I should do dynamic load test instead of static load test, as I know the result is the same and also I know how it is tested by authorities = by static test). I understand it is sometimes hard to get all the info and facts out from the pictures provided, maybe this might be also a problem here.
No offence.