It would better be said that there is no provision under the Constitution authorizing the SPECIFIC punishment of those who counterfeit securities of other nations.
There is, however, a GENERAL provision which authorizes Congress to punish such acts. It is the provision that authorizes Congress to punish “offences against the law of nations.”
And that phrase in our Constitution doe NOT come from Vattel. It comes from Blackstone, the writer on the English common law, who included an entire CHAPTER with that TITLE in his work.
And this is CLEAR by the other terms used in that provision of the Constitution all of which are found in Blackstone’s work on the matter, and almost none of which are covered by Vattel.