Their conditions were not prohibited by the agreement, and they clearly stated them as a condition to being bound. Legally, that is acceptance. If not, then they were never bound to begin with.
Instead the clauses in the ratification document were a one-sided assumption of what was permitted under the Constitution.
Not at all. The clauses were very clearly stated conditions placed upon their being bound to the union. They were a 'binding' part of the agreement.
The Constitution was the final word on what was legal and illegal and the Supreme Court ruled that the path that Virginia chose to follow in 1861 was illegal.
For that to be a legal ruling, the Justice's "consensus of states" BS would have to be part of the Constitution or the documents that bound the States to it, which it is not. The documents binding those States to the Constitution very clearly show that it was the individual State's decision. The agreement and the documents associated with it directly contradict that ruling and show it to a direct violation of the original agreement. It is an illegal ruling or the union is void as a fraudulent agreement.
You still have it backwards. The states were accepting the Constitution as adopted by convention. The fact that they chose to place assumptions in their ratification documents did not mean that those assumptions were valid, or that they could be exercised in whatever manner the state chose. If may be perfectly legal for a state to resume power to itself and leave the Union, but if the state chooses to do so unilaterally then their actions are illegal because they violate the Constitution.
For that to be a legal ruling, the Justice's "consensus of states" BS would have to be part of the Constitution or the documents that bound the States to it, which it is not.
It is a legal ruling, regardless of whether you agree with it or not. The Constitution vests the Supreme Court with interpreting the Constitution, not you or I, and the fact that you think its BS means absolutely nothing. The Supreme Court determined that secession as practiced by the southern states was illegal because it was done without the consent of the other states. That's all there is to it, unless the Constitution is amended or a future court overturns the decision.