Couple ideas here:
1. Couldn't the 'Is Onscreen' condition benefit from render cells by only looking thru onscreen cells?
2. Here would be an interesting new system condition: 'Pick by distance from point'. We could then specify a x/y point, a distance, and a comparator (<,>,=,etc...). This could work with/without render cells, but it would obviously be faster with them.
3. There could also be a similar condition: 'Pick distance between', where we could define a min/max range to pick objects from (imagine a zone shaped like a torus). Again, this would use render cells where enabled to limit the number of objects that need to be queried.
Both of these would help to process local objects on large layouts, by providing an efficient way to pick and sort thru them (assuming said objects are on a layer with render cells enabled).