Topic on Help talk:Extension:CollaborationKit

to change the icon for a feature. If I knew the name I could do it in the hub manager, but where are the names listed?

The names are the ones listed here: https://github.com/wikimedia/mediawiki-extensions-CollaborationKit/tree/master/modules/images/icons but without the ".svg" part. (Clicking on them will show you a preview.) From there you can substitute out the keyword from editing the Collaboration Hub, for example by changing image=discussion to image=community. Or you could do image=Custom_file.svg to use an on-wiki image.

(As an aside: the icons with names should probably be documented in a more "on-wiki" way.)

Each wiki with CollaborationKit installed now has a special page, Special:CollaborationKitIcons, showing each icon and its name. https://wpx.wmflabs.org/w/index.php/Special:CollaborationKitIcons