This particular question doesn't make sense because the courts could not rule that an amendment to the Constitution is unconstitutional as it would be by definition constitutional. Of course these days I wouldn't put it beyond the realm of possibility with the nonsense rulings we've been seeing lately.
Time to think holistically:
Suppose a Convention of States were called, and suppose a delegation is created by a state, say Texas, that consisted of a bunch of white guys and gals to represent the State of Texas at said convention.
What is the first thing the liberals are going to do before that convention even meets?
Can you now understand how the delegation to the convention just became mixed up? Can you see how state lines no longer matter?