> How do you know that was an unanticipated effect?

Wanting to support Berlin so that the communist regime would eventually collapse might be a desired outcome, but the way it happened couldn't have been anticipated, it could at most be wished for. Wishfulness is the very thing the parent article is arguing against.

> How can you tell a priori wether intervening will have good results?

You try to learn history and figure out parameters for successful predictions?

> Moreover, if you're a decision-maker, will you bear any cost if your decision turns out wrong? If not, how is that supposed to be ethical?

I don't disagree? Ethics effects exist to encourage people to take precautions when it comes to the effects of their actions or inactions. There are obviously entrenched interests that push back against ethical consequences.