The weights must still have some understanding of the chess board. Though there is always the chance that it makes no sense to us

Why must it involve understanding? I feel like you’re operating under the assumption that functionalism is the “correct” philosophical framework without considering alternative views.

Even that is probably too much. It has no understanding of what "chess" is, or what a chess board is, or even what a game is. And yet it crushes every human with ease. It's pretty nuts haha.

Actually, the neural net itself is fairly imprecise. Search is required for it to achieve good play. Here's an example of me beating Stockfish 18 at depth 1: https://lichess.org/XmITiqmi

chess is just a simple mathematical construct so that's not surprising

There is no understanding, the weights are selected based on better fit. Our cells have no understanding of optics just because they have the eyes coded in their DNA.

Does Stockfish have weights or use a neural net? I know older versions did not.

yes

The ML techniques it uses are only about evaluation, but you were close