I actually didn't even know that the wilson score was missing from Custom filters. I guess custom filters were built before we added wilson score to the site. Custom filters actually never really got finalized either.
I have bookmarked this topic. I would also like to add "normal" favorite-point-filters to the system. And as you have been speaking about before, a cache owner filter (this has been planned for a long time as well).
As you may start to realize, we have a lot of plans, we just lack the time. :/