Are you using flight trajectories with simulated drag and lift from Magnus effect?

Yes! it does do the math for Magnus effect. Source code is all client side you can take a look at it.

But early on when I started this, I prompted the LLMs strongly to focus on having accurate real world physics baked in.

Nice! Why I can only select the angle in multiples of 5°? I expected to be able to rotate the blade just a little.

For "Back Spin" I used: angle = open 50°, Brush = -20° down, Speed = 13 km/h and I got a success "Lands - Smash Food". Do you have a table of the possible classification?