The Western narrative of China is a bubble of alternate reality. This RCEP event shows you just how alternate it is.
Sovereign nations don't have foreign occupation forces. Japan and SK are occupied client/vassal/satellite states. We can call them allies if we want to save face, but if china or russia had occupation forces there, we'd call them vassals or satellites or client. Ultimately that's what they are.
We'd never call warsaw-pact nations sovereign states, wonder why we call japan or sk sovereign states?
There are no sovereign indigenous nations in australia. You will not find them as members in the UN, you will not find them on maps, they cannot form any sovereign treaties with other nations, etc.
The idea of "sovereign indigenous nations" is just virtue signaling. Maybe one day they will be free and sovereign nations, but I seriously doubt it.