The Kentucky resolution is just clearer. Let's look at just the Virginia resolution, shall we? Remember your claim is that the Virginia resolution is NOT evidence for the idea that a single state can nullify a Federal law. Let's see what the Virginia resolution says, in relevant part:
"[T]he General Assembly doth solemnly appeal to the like dispositions of the other states, in confidence that they will concur with this commonwealth in declaring, as it does hereby declare, that the acts aforesaid, are unconstitutional; and that the necessary and proper measures will be taken by each, for co-operating with this state, in maintaining the Authorities, Rights, and Liberties, referred to the States respectively, or to the people."
We see two things here:
i) It absolutely does appeal to other states, that's true;
ii) but it appeals to them to declare the law unconstitutional AS VIRGINIA HAS ALREADY DONE UNILATERALLY.
So we see that your initial claim that this is not historical evidence for the idea that a single state can nullify a federal act *plainly* contravenes the text of the Virginia resolution, which is the less clear of the two on this point. The Kentucky resolution is even more explicit. (Because while the Virginia resolution does explicitly declare a federal act unconstitutional, the Kentucky resolution actually says in general that there is a right on the part of a single state to nullify.
Although the VA resolution does contain this pretty strong language, too:
"[A]nd that in case of a deliberate, palpable, and dangerous exercise of other powers, not granted by the said compact, the states who are parties thereto, have the right, and are in duty bound, to interpose for arresting the progress of the evil, and for maintaining within their respective limits, the authorities, rights and liberties appertaining to them."
This part is just ambiguous as to whether it refers to "the states" severally or individually. In the context of the rest of the document, the interpretation that makes the most sense is that each state, and so in particular all states, are bound to do it; so Virginia is doing it, and entreats the other states to join her.
You're absolutely right that Madison later contradicted this position. Madison is a person who demonstrated inconsistency on quite a few things over his lifetime.