"how do they defeat the speed of causality to relay information back home?"

Why must 'they' (assumption there) 'defeat the speed of causality', exactly?

Even at light speed, the information will beat any physical threat to the home region, permitting some kind of response.

Also, the idea that 'causality' is bound to the speed of light is, in my opinion, simply a result of our limited understanding. Just as relativity opened new vistas, it is likely a new theory explaining gravity, dark matter, and dark energy will provide entirely new, fundamental understanding - and possibly FTL communication/travel.

Anyone capable of sending such a thing would have more than one home, plenty of time to respond, and likely some kind of automated military hub every X light years as an early response force. We certainly would if we could.

Subspace communications of course (don't you watch Star Trek?)

In my theory they don't. They are autonomous and surveil the galaxy for emergent tech that could destroy all life and if discovered, wipe it out.