My first attempt at hanging failed ...
So I have the two fasteners again quite solved - that was easily and cleanly - and the tiles cleaned briefly.
At this point My tip: Before hanging wipe again with a limescale on the tiles!
On the second attempt the shelf sat bombproof - and do it after just one week heavy load still.
Conclusion currently: I am definitely convinced of this system!
I had in front of the other system of "Never again drilling" - was dropped once or elsewhere should be fixed, you had to buy more again for about 6 euros the expensive system with the adhesive paste. I am glad that it is no longer so now. If anything changes, I will of course describing this here!