Basically it's mostly that I followed what I thought I understood from the wiki!
It is not so obvious to understand that in reality it is not necessarily a file category by namespace.

How is it going in the yml of the category ?
How do you place multiple namespaces there?
namespace: A,B,C
Or
namespace: A
namespace: B
namespace: C
No matter what I test, the IA VSC editor underlines it in red as it was an error so like before, I don't understand how to format this 😕