In my understanding you can definitely point to some tx and say that has something to do with the other party. But if there is a "contract" between two companie

In my understanding you can definitely point to some tx and say that has something to do with the other party. But if there is a "contract" between two companies, like company A should give this in these circumstances to company B. If there is then a dispute about these circumstances, it matters whether the contract was on paper with actual signatures (a document designed to be able to be enforced by law) or a "smart contract" on a blockchain system somewhere. In case of the latter you cannot say "I want my money because the contract says so" if the contract only exists as a smart contract on a blockchain. If it's on paper the decision might be based on the actual wording (in English or another language) - this is all very hard when you're dealing with a programming language (or set of instructions). But as I said, IANAL.