Right now, harm seeker in the hornet implementation can magically see and instantaneously update all air defences in its fov. This is somewhat unrealistic, since harm seeker needs to sweep through its fov like a radar would do, and that takes a significant amount of time. That's why there are filtering and azimuth limiting options, just to make the sweep faster.
The difference however, and this is my own guess, is that in the hornet the CLC can store harm contacts and make the math to present them with regards to missile boresight in each moment, so it's not a static image. But not sure about this one