i) One of the stock objections to Calvinism is original sin–especially the imputation of Adam's sin. How is it fair for us to be held responsible for the actions of another? We weren't party to his actions. We didn't consent to his actions.
Strictly speaking, this isn't a problem for Calvinism. Assuming, for argument's sake, that it's problematic, this is a problem for Scripture. It's only a problem for Calvinism inasmuch as Calvinism is one of the few remaining live theological traditions that still takes seriously what Scripture says about original sin. So this is less about Calvinism than the inspiration and authority of Scripture.
ii) That said, let's consider the objection on its own terms. For ease of reference, let's call this the principle of vicarious responsibility
Certainly there are many situations, or kinds of situations, where vicarious responsibility would be unjust. In fact, the Bible itself regards vicarious responsibility as unjust in some situations (e.g. Deut 24:16).
iii) But is that a universal principle? Let's consider a hypothetical case. A wife has a child by another man in the course of an illicit affair. There is, however, no immediate reason for her husband to suspect that the child isn't his.
10 years later, the boy falls ill and undergoes some tests which incidentally disclose the fact that the boy isn't the husband's biological child.
The wife, realizing that her husband will never view her the same way, leaves her husband for the man the truly loves. And she leaves her son behind in the care and custody of her ex-husband. She never wanted the child.
Although this is hypothetical, there are real-life examples that correspond to this type of situation.
What are the responsibilities of the husband in this situation? One option is leave the boy with his biological mother and father. Drive the boy to wherever they are living, and hand him off to them.
Surely, though, it's too late for that. For 10 years, the husband has been the only father the boy has known. His biological father doesn't know him or care about him. And his mother doesn't care about him.
So the boy needs the husband to continue to be a father to him. It would be detrimental to his psychological development to rip him out of that relationship and thrust him into the hands of two uncaring adults.
Here's a case where an individual becomes responsible for the consequences of someone else's misdeed. And this is despite the fact that the individual was wronged.
We could cite analogous examples. Take a foundling. A desperate mother places her newborn on the doorstep of a well-to-do family, hoping they will care for the child. That shouldn't be their responsibility. But now that it's been thrust upon them, it is their duty to rise to the challenge.
As such, I don't think vicarious responsibility is unjust in principle. It's easy enough to come up with counterexample in which it seems to be a moral obligation.
Of course, these examples appeal to intuition. Some people might reject the intuition. However, that cuts both ways. For the objection to original sin is intuitive too.