There are other things aside from array broadcasting that languages stand to learn from APL. I think that the biggest one is looking carefully at the clever choice of primitives.

To my knowledge other languages like Julia and numpy don't offer the same range of index-based primitives, like grades, or classifications, which are used pervasively in APLs.

APLs better support a pattern of computing some permutation of a set of arrays, and then viewing other arrays through that permutation, than other languages. You can do it, of course, in numpy, but it's not nearly as pleasant.