>International law is not a real thing that has loopholes... it is just a set of agreed upon principles that are usually followed

Nation states exist in a state of nature, and unfortunately might usually makes right. Superpowers can, and often do, simply decide that aspects of international law just don't apply to them. Of course, that doesn't stop them holding weaker powers to those standards.

Sounds more like an International Wishlist. Wherever the venn diagram of What a Country Does and What the World Wants intersects, they pat themselves on the back. Everything else, they shrug. I wonder what's the point.

That is exactly point; so that at least everyone agrees beforehand when praise/condemnation is appropriate. It doesn't enforce itself, but it does at least provide a notional focus point. Countries do attempt to reward and punish each other in various ways, and "international law" gives some direction to it.