I have a very different approach to this stuff. I understand "sound", but I approach it my own way. I suppose you could say I take the hands-on approach to it all, not the scientific one.
It's sound after all, so as far as I'm concerned it's all about what I hear. That's been my own way of learning physical modeling. I listen to a sound and sort of put it into mind slots if you like. Think of the various types of synthesis out there, they each have a slot and when I hear sound, it falls into one of those slots. I take it from there, progressing as it becomes more and more obvious which type of synthesis are required to model a specific aspect of an instrumnents sound.
I used to play around with this a lot back when Reaktor was at version 2, so I'm currently having to re-igniting my brain after being dropped into Axoloti after all that time.
Now you're going to laugh at me here (oh yes you are), but physical modelling, even though I've been getting by without functions for all this time, is actually quite easy for me. I find it fun in areas where I can imagine others might find it completely frustrating. I suppose what I mentioned earlier comes into play as well, about certain advantages of being a high-level thinker.
That's kinda why I asked about the websites, I've faced the same problem as you have in finding them. It's something that interests me greatly, but almost everything out there takes the scientific/mathematical approach, whereas I don't.
Already intended to read your WSA stuff, and will do, just haven't finished the CS80 one yet