I use Find in Project ( ⌘ ⇧ F ) a lot, but clicking on each result is cumbersome. I know that there is ⌘ G to go to the next search result in the current open file.
Is there a shortcut to go to the next search result in Find Navigator?
This is not true. If you open Preferences and click "Key Bindings", you will see all the possible menu commands and set the keys for them. In the menu "Find" there is no command "Find next in the workspace", only regular "Find next."
You can always press ⇥ (tab) once (focus on the results, although there is no visual indicator), and then ↑ or ↓ to move between the results.