This is a tough problem to solve. One approach I’ve had success with for this kind of “diffuse accountability” problem is to make this a rotating role that one person does. Eg if you have a release per week, have a BuildMaster hat and part of the job is figuring out which things to backport. The hat rotates so people take turns thinking about the thing a lot, instead of everyone having to spend a couple cycles on it. If someone is wearing the hat and messes up then that is a more focused performance problem you can pinpoint and remedy.

Of course this doesn’t always work for every problem, just an idea that may work for some instances of this kind.