Exactly right.
For something like the ratification of the Constitution, where the provisions were debated hotly at the state levels, you would have to look at the most commonly understood meaning of words and phraaes used in the Constitution across the colonies as a whole.
I would think the understanding of Philadelphia/Pennsylvania would be the most definitive because *THAT* is where the convention was held, and *THAT* was the US Capitol at the time. The states talked to each other. It is completely reasonable to believe that what Philadelphia Pennsylvania thought was the meaning was also what other states thought was the meaning.
Were it otherwise, it would have provoked a dispute over the meaning.
I don't agree. There was no internet, or any national newspapers to spread that kind of word from state to state. And if there were, there should have been a record of it somewhere, and yet we've never seen it.
The one commonality when it came to understanding legal terms across all the colonies was the prevalence of the English common law system. That was The legal system that was the foundation of law in every single colony, and something with which voters and representatives in every colony would have been familiar.
Therefore, the meaning of any legal terms under the English common law system would have been far more likely to be reflective of common understanding than where idiosyncratic definitions used by some particular people within a particular colony.
Wasn’t New York City the Capitol in 1787? Congress met there and Washington was inaugurated there in 1789.