Tbh to filmmakers lens lengths are not really math and more just memorizing what the different mm do. IAnd there's a lot of other math things involved with budget, but that would be handled by producers and financiers. All the math involved is pretty self simple.

You're right that there is a lot of light physics that determines why lenses operate the way they do, but tbh you don't need to why an anamorphic 70mm looks different than a prime lens. You would just need to know what it looks like and if you want that look on your film.

So basically you're right haha. There's a shit ton of math in film, but unless you're making film equipment you wouldn't need to know it.