But they or "we"
are trying to detect actual gravity communication.
Think of LIGO
https://en.wikipedia.org/wiki/LIGO as antenna for that special language / communication medium, no?
I like the way you think and express your thoughts. But it's a bit harsh assuming we are not trying to detect it at all.
LIGO doesn't necessarily have to be the antenna for actual gravitational communication.
It might "only" be an antenna for the result of such a communication when it influences its environment of known-to-us communicators and makes them whisper to each other: "Hey, have you heard what happened in a galaxy far far away?"
The disturbing thing - in your line of thought disturbing, I assume - with LIGO's 12 detections is that the sources were of 2 items which only "exist" theoretically to explain away gaps in the standard model: mergers of a) black holes and b) neutron stars.