Judges don't get elected in the US (except for some state and local judges) and yet the US is a superpower. I don't think judicial selection plays a major factor in determining superpower status.
Can you name any country that has ever been a superpower where judges (of the national judiciary if it has separate judiciaries for constituent parts from the national one) were predominantly democratically elected?
Can you name any country that has ever been a superpower where judges (of the national judiciary if it has separate judiciaries for constituent parts from the national one) were predominantly democratically elected?