Yes, Editors can update published Packs.
You can re-publish packs at any time which will let everyone in the Room know about changes.
One gotcha to note is that while you're making changes to a published pack the changes will be visible to everyone, because that pack is already published. If this is 'not excellent' then the best path forward is to clone an existing pack (cloned packs will not be published by default), make the edits, then publish that as 'Pack v2' or 'Pack v1.x' into the same room.
You can also un-publish a pack at any time, which will restrict access on that pack to room Owners and Editors.