They still don't matter from our point of view, since everything outside the hubble sphere is by definition completely causally disconnected from us due to moving away from us faster than light.
The main value of these sorts of detections is towards probing the early ages of the universe and how quickly certain things formed, in which context, the idea of a larger black hole beyond the edge of the observable universe doesn't make much sense, since the edge of the observable universe is t=0 for the big bang (to be precise, the edge observable via photons is actually t=~370k years, the point where the universe cooled enough to be optically transparent, but theoretically we could look to t=~1 second if we could devise a way to detect relic neutrinos from the big bang).
It sort of does because it had an impact on the formation of our part of the universe in the beginning, sorry it is useful in understanding the formation of the universe
The main value of these sorts of detections is towards probing the early ages of the universe and how quickly certain things formed, in which context, the idea of a larger black hole beyond the edge of the observable universe doesn't make much sense, since the edge of the observable universe is t=0 for the big bang (to be precise, the edge observable via photons is actually t=~370k years, the point where the universe cooled enough to be optically transparent, but theoretically we could look to t=~1 second if we could devise a way to detect relic neutrinos from the big bang).