is tracking converting all configuration that has multiplicity into the ConfigEntity system. I.e., image styles, text formats, views, account email templates, etc. are all examples of things that different sites can have different sets of, which requires the "C" and "D" part of CRUD, and in general, fits the concept of entities (in the broad sense of the word, not the more limited D7 sense).
However, we also have configuration objects like system.site.yml, for which every site only ever has 1 of. So far, consensus has been that these should not be ConfigEntities. One of the consequences of that choice is that configuration translation requires a completely separate concept/implementation/API/UI than entity translation.
In, fago says:
I could see the simple settings being each own config entity as well.
Let's discuss that in this issue.