I don’t mind seeing a long list of curators with 0s, so that’s not a huge issue for me unless that’s what’s causing people to intermittently disappear. As for what stats should be included, I think taxon changes committed is more helpful than added (and you can’t search for changes committed either). Having taxa added would also be good, or make it clear that taxa curated includes that (right now I’m not sure if it does). The only other curator-specific actions I can think of are user (un)suspension (not sure that needs to be publicized) and name editing (also under taxa curated?). Not sure what does or should happen regarding unresolved flags or deleted taxa.
Here’s some related threads:
https://forum.inaturalist.org/t/remove-all-curators-and-start-from-scratch/140
https://forum.inaturalist.org/t/im-missing-from-the-curator-section-of-the-people-page/11392
https://forum.inaturalist.org/t/taxa-curated-number-lower-than-it-should-be/27763/10