Wunderlist2 remove local database, so old extensions don't work anymore. Here is the one that will work with Wunderlist2.

Wunderlist2.alfredextension

on alfred_script(q)

  set the clipboard to q
	tell application "System Events"
  	tell application "Wunderlist" to activate
  	tell process "Wunderlist"
  		click menu item "Add New Item" of menu 1 of menu bar item "File" of menu bar 1
  	end tell
  end tell

  tell application "System Events"
  	keystroke "v" using {command down} --Command-C
  	keystroke return
  end tell

end alfred_script