No it’s wrong it doesn’t work the way you describe.
Zoom to Selection will only work if something is selected and when you open the editor nothing is selected!
You have to select one or more MIDI event(s) - Command+A. So in total:
E to open the editor
Command+A to select all events in the part
Shift+Z (my command for Zoom to Selection)
AND then Shift+Command+A to deselect all events. 
Believe me I have created all the macro you can suggest, but when I thought all the time spending on programming macros, setting up Metagrid working with Project Logical Editor, was supposed to be a “set and forget” thing - and I will eventually forget - it’s a constant challenge to fix all the small things that shows up.
Let me give you an example - you might even have a solution!
In C13 we have the all new Channel Tab to the left of the Inspector. That broke my Metagrid set-up because as long as there are no key command to select the visibility/Inspector pane I have created a Keyboard Maestro Macro to move the mouse up to “Visibility”/“Inspector” text and click. This macro also select the track below the present track and goes back again to force the visibility tab to link to the selected channel. By default the visibility pane dosn’t sync with your selected track in the project!
After the new channel this macro needs repairing because the mouse coordinates in the macro no longer match the text “Visibility”/“Inspector” text!
Working with a 900 track template will demand some clicking I admit, but the way Cubase is designed could be improved, right?
I mean wouldn’t it be nice to have a preference for sync between the visibility pane and the track selected in your project, I can’t imagine that I’m the only one who would like that?