"How far is Natural semantic metalanguage really natural?"
"How much is Natural semantic metalanguage really natural?"
Can I use any of these sentences to express: "To what extent is Natural semantic metalanguage really natural?"
"How far is Natural semantic metalanguage really natural?"
"How much is Natural semantic metalanguage really natural?"
Can I use any of these sentences to express: "To what extent is Natural semantic metalanguage really natural?"
Maybe you mean just:
"How natural is Natural semantic metalanguage?"