What's so hard to understand?? Minor said "Some authorities" go further and declares as citizens children born in the country WITHOUT regard to the citizenship of the parents. This group of citizens might include NBCs, but for those who aren't, there is doubt about their citizenship. It doesn't say "some authorities" declare these persons to be natural born citizens, just citizens. For that class of citizen there is doubt, but some that can be resolved, some that can't.
Explaining again how you read it doesn't help me understand how you could read it that way. Why would the court bother to make the distinction between NBC and "regular" born citizens at this point? Minor wasn't running for president, she just wanted to vote--"regular" citizenship would have been fine for that, and introducing the term "natural born" would be unnecessary.
Also, right after the sentences we're talking about, they write, "It is sufficient for everything we have now to consider that all children born of citizen parents within the jurisdiction are themselves citizens." That wording--"all children born of citizen parents within the jurisdiction"--is what you claim defines an NBC, and yet the court doesn't say "natural born" again. You claim they've just finished making this vitally important distinction between two types of born citizens--and then they immediately drop the subject.
Sorry, to me it's obvious that the whole section only makes sense if they're using "citizenship of the United States...by birth," "new citizens...born," "natural-born citizens," and "became themselves, upon their birth, citizens" to mean exactly the same thing. Otherwise you have them veering wildly among classes of children and classes of citizen for no good reason.