Um… I can’t recall how I added those shortcuts for the snippet items…
Now I see: It warns only when I changed the shortcut and confirm the dialog.

However, issue 3:
The warning can be bypassed:
Open the Properties of a snippet.
Add a shortcut that conflicts (e.g. Ctrl+N).
Then enable “Use Default Shortcut”.
Confirm and reopen the dialog.
Disable “Use Default Shortcut”.
Confirm the dialog.
** It doesn’t warn.

However again, issue 4:
** Clicking “Edit” button in the dialog always triggers the warning if the shortcut conflicts.
I don’t think it’s necessary.