This is the way I get Cubase to load the most recent project. It’s assuming that Cubase is already running.
Create a macro in Keyboard Maestro, add Execute AppleScript event, and fill in this code:
tell application "System Events"
tell application process "Cubase"
click menu item 1 of menu "Recent Projects" of menu item "Recent Projects" of menu "File" of menu bar item "File" of menu bar 1
end tell
end tell
You can then assign it a global keyboard shortcut. I assign it Cmd+Shift+O which is Pro Tool’s open recent command.