Ultimately, the answer is that the Archivist of the United States gets to decide what "ratified" means.
A valuable lesson can be drawn from the adoption of the 27th Amendment - one which was unorthodox, in that it was actually a part of the Bill of Rights, but didn't get "ratified" by 3/4 of the states until 1992. Quoting Wikipedia's Artcile on the 27th:
On May 18, 1992, the amendment was officially certified by Archivist of the United States Don W. Wilson. On May 19, 1992, it was printed in the Federal Register, together with the certificate of ratification.[7]
Speaker of the House Tom Foley and others called for a legal challenge to the amendment's unusual ratification.
In certifying that the amendment had been validly ratified, the Archivist of the United States had acted under statutory authority granted to his office by the Congress under Title 1, section 106b of the United States Code, which states:
Whenever official notice is received at the National Archives and Records Administration that any amendment proposed to the Constitution of the United States has been adopted, according to the provisions of the Constitution, the Archivist of the United States shall forthwith cause the amendment to be published, with his certificate, specifying the States by which the same may have been adopted, and that the same has become valid, to all intents and purposes, as a part of the Constitution of the United States.
Despite that, Senator Robert Byrd of West Virginia scolded Wilson for having certified the amendment without congressional approval. Although Byrd supported Congressional acceptance of the amendment, he contended that Wilson had deviated from "historic tradition" by not waiting for Congress to consider the validity of the ratification, given the more than 202-year lapse since the Amendment had been proposed.[7]
On May 20, 1992, under the authority recognized in Coleman, and in keeping with the precedent first established regarding the ratification of the Fourteenth Amendment, each house of the 102nd Congress passed its own version of a concurrent resolution agreeing that the amendment was validly ratified, despite the unorthodox period of more than 202 years for the completion of the task. Neither version was adopted by the entire Congress.
In other words, the Archivist decided what "ratified" meant, and the Congress got annoyed that he made the interpretation without them. That said, legally, he had a strong case - one that ultimately SCOTUS would have had to decide, had Congress disagreed.
Note, the "Titles of Nobility Amendment" likewise suffered from questions about whether or not enough states had duly ratified it. In fact, there was a point at which the threshhold had sort of been reached - but in the cases of both Virginia and South Carolina, only one house had passed it, not both. As such, no governor had to intervene keeping any "Esquire" from losing his citizenship. And, in the end, it was the Supreme Court that said it had never been duly ratified.
According to the Harvard Law Review, the ambiguity of Article 5 is historical in nature:
Much of the confusion about Article V comes from its ambiguous language. This ambiguity is the result of compromises at the Philadelphia Convention of 1787 between groups that wanted to exclude the national legislature from participating in the amendment process and groups that wanted to grant the national legislature the sole authority to amend. The earliest proposal for an amendment provision, contained in the Virginia Plan, stated that “the assent of the National Legislature ought not to be required” to amend the Constitution.'5 Convention delegates privately circulated a proposed constitution authored by Alexander Hamilton that gave the power to amend the Constitution to the national legislature and the power of ratification to legislatures or conventions in the States.
The Convention's first official action regarding the method for
amending the Constitution was to adopt Resolution 17, which
stated that the Constitution should contain some means for
amendment, but did not specify the particular process to be
used.
In other words, this may have been a case where the ambiguity over whether each State Legislature needed to get the assent of the State executive was intentionally left vague.
The nature of federalism has, in any event, long since changed, but the general idea has always been that States get to make their rules and the federal government gets to make its own rules in regards to how it makes legislation.
Note finally, Article 5 states simply that
The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Constitution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as Part of this Constitution,
when ratified by the Legislatures of three fourths of the several States, or by Conventions in three fourths thereof,
as the one or the other Mode of Ratification may be proposed by the Congress; Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.
Thus, to propose an amendment you need:
- Congress to pass by super majority an amendment to send to the states (most common) or
- Two-thirds of the states to ask for a convention.
Once proposed, 3/4 of the states must ratify - but what that means is apparently, at present, up to David Ferriero to decide.