IXALU, welcome to the Wicked Edge forum. My ability to read and understand Spanish is very basic, and not all that good. But I’ll try.
The wear you are showing with the photos is normal and just what is expected. Just what I experienced, also. The ceramic stones do take a while to break in and require a lot of use till they yield their best results. The stones do have a residue or coating left on the surface from the manufacturing process.
You can rub the like-grit ceramic stones together “dry”, stone flat against same stone, to help remove the residue and speed up the break-in period.
I hope you understand this or you can get this translated. I believe this should help answer your questions.
Maybe a Spanish speaking forum member will step in to help.