I have selected a file in the Project Navigator, default shortcut is ⌘+1.
Then through something (like focus to debugger, jump to another file with the top bar) the open file in the source editor changes.
I know I can ⌘+J and the open file in the Editor will be selected in the project navigator.
But how to make it the opposite way, jumping to the selected file, without using the mouse?
There is no shortcut and since it is not always the same direction (up or down) nor the same steps it can not be automated.
But you can navigate with the arrow keys in the project navigator at least without loosing the highlight of the last opened file.
So instead of Reveal in project navigator, use cmd+1 to focus the project navigator and then just use up/down to navigate.
With left you can navigate to the next higher group.