A very good argument can be made to the effect that the document that you seek, a consulate certificate, does not create either the citizenship or the natural born citizenship but merely documents that citizenship and natural born status. If so, and no certificate was issued to a child who was otherwise qualified, that child is nevertheless a natural born citizen by right and can obtain the certificate and any time.
Finally, the idea that Cruz can go into court for a declaratory judgment is simply wrong. The courts will not issue a declaratory judgment in a political situation.
Cruz is a ‘natural born’ Canadian. He will never be a ‘natural born’ US citizen... and Cruz knows this, as any Harvard Law Schooled grad knows... Lawyers live to change the law... But lawyers nor judges can give or take ‘birthrights’.
Not sure which cases you are referring to, but the remarks in born-abroad citizenship cases aren't dicta. The remarks reflect an essential premise for grounding the decision.
By way of example, a case might be decided on sufficiency of a jury instruction. Remarks in the case indicate there was a trial. Are those remarks dicta? I mean, without a trial, there would not be a jury instruction, and there would not be an argument about the sufficiency of the jury instruction. It is essential for the premise to exist, which makes the remarks "not dicta," as dicta refers to material that is not essential or necessary to decide the case.
Same principle applies in born-abroad citizenship cases. A necessary premise is that the person be naturalized in the first place.
Educate yourself.