That’s normal, because in Python a method can return virtually anything. That said it’s not possible what object self.ground is until the code is executed and at that spot.
You can only do code completion for classes or objects that obviously are of a certain type - and even that is not really reliable, because in Python everything is so dynamic (you can even change the methods of a class or of an object from outside).
By the way, you don’t need to set up a project, configure anything or even install the add ons from the post above. The code completion works out of the box with only SublimeCodeIntel add on installed. At least that works for me on Linux (where you don’t have to worry about python paths anyway 
).
Still thanks for the tip with the SublimeCodeIntel add on 