Honestly I doubt any size anything linkshell related could ever solve it all, but certainly could help (people finding something and attempting to do it on their own will not be reporting it of course, so in that any number of shells will not help). I can imagine the wonderful drama that could rise out of very large mandatory cross world hunt shells though

.. XD..
But you're saying an in game tracker could solve these issues? So besides time of death it sounds like you were also suggesting it notifies people that a monster is up (from reading OP), yeah?
Just curious if the info was public do you think it would be okay for people to try to do it on their lonesome? Or is that sort of activity part of the problem?
Just wanted to add cross-world link shells will get an expansion in Shadowbringers (8, iirc).