Xcode commit view: keyboard shortcut for jumping to the next change?
I'm unsure of the version that this feature became available, but you can jump to the next and last change of the currently viewed file (Navigate -> Jump to Next/Previous Change). The shortcut is ^ \ for next and ^ | for previous.

This can be used on Standard and Assistant editor, but NOT Source Control Editor.

I can confirm that this feature is available in Xcode 10.1 and Xcode 10.2