No, it doesn't if you mean with "exactly these decisions" that it also decides what words are considered officially part of the language. You also got the name

No, it doesn't if you mean with "exactly these decisions" that it also decides what words are considered officially part of the language. You also got the name wrong. It's "Rat für deutsche Rechtschreibung" (Council for German Orthography) and that is exactly what they do. They standardize on the orthography. Nothing more.