Posting her tax return can do several things. It can bring “sunshine” to their finances. It open’s up these finances for everyone to see, including the one’s who gave money to the Clinton’s.
If there would be a DISCREPANCY of some kind, it would then be more likely become a problem for someone.
It would not tell you what you need to know. It would only tell you what their total income is, how much is from investment, how much for services, and what kinds of deductions they take. It would not tell you where the income came from. I suppose that if they supplied the W-2s and 1099s, it might tell you who paid it to them, but probably not why. And foreign companies probably would not even provide a W-2 or 1099.