If by “understand” you mean “can model reasonably accurately much of the time” then maybe you’ll find consensus. But that’s not a universal definition of “understand”.
For example, if I asked you whether you “understand” ballistic flight, and you produced a table that you interpolate from instead of a quadratic, then I would not feel that you understand it, even though you can kinda sorta model it.
And even if you do, if you didn’t produce the universal gravitation formula, I would still wonder how “deeply” you understand. So it’s not like “understand” is a binary I suppose.
I think it’s just that’s the word you’ve been taught to use. It’s divorced from the meaning of its constituent parts, you aren’t saying “an American of African descent” you’re saying “black” but in what was supposed to be some kind of politically correct way.
I cannot imagine even the most daft American using it in the UK and intending that the person is actually American.