Whether congress understood NBC according to the Law of Nations or English Common Law, in either case, Cruz wouldn't qualify. Under ECW, citizenship does not derive from the mother, but through the father. Under the law of nations, Cruz is disqualified because he was not born in the US to two citizen parents.
By the way, the 1790 act was amended and its "natural born" language specifically removed, probably due to Congress realizing that the British were using it to justify impressment. The founders did not want people upon whom dual claims of citizenship can be made.
The point isn’t who Congress chooses to confer citizenship upon, but their definition of natural-born. At the time of his birth, Cruz was a citizen; thus, he is a natural-born citizen, as opposed to a naturalized citizen.
I think the Court would hold that the distinction between the citizenship of the mother and the father at English Common Law is no longer valid, based on the 14th and 19th Amendment.