At the moment it is not possible to write a checker for this cache. With the methods currently available to checkers, it is only possible to look at the finds of the current user, not other caches. That means that it is not possible to find out which are the top 50 (or whatever number) caches with the best Wilson scores. It could be possible that methods to do that are added at a later stage, but right now a checker for this challenge is not possible.