“Naturels is in the 1758 French edition.”
And it was translated ‘natives’, when it was finally translated AFTER the Constitution was written. ‘Naturel’ would translate differently than ‘sujects naturels’, which conveys the phrase ‘natural born subject’...and it could only support NBC IF NBC is the equivalent of natural born subject, and if Vattel had written ‘sujects naturels’ instead of ‘naturels’.
But if you go that route, then you have to deal with common law, with NBS including the children of aliens...which would make Barry a NBC. So you don’t want to go there.
Thhe Founders translated naturels to corn, seaweed, cornbread or natural born?
He would have written cityons naturels, but sometimes things are just understood in the context of the paragraph. In that case the paragraph/section was talking about Citoyens/Citizens, so that is what the adjective "naturels" had to be modifying (in the grammatical sense, as El Lobo Azul, (meaning the Blue Wolf, with Azul modifying Lobo) . It was certainly not modifying "subjects"/"sujects", which does not appear in the section.