If you look at Google Earth closely, you will see that the only crosswalk to the walking path on the other side of Buena Vista is at the gated entrance to CSR. That's unfortunate, because depending on where within the resort you are starting the walk, there may be a much shorter route, but you would have to take your chances crossing Buena Vista without a light; always a risky proposition on Disney property.
If you look closely on street view, you will note that at the far end of CSR's convention center building parking, there is an open un-landscaped area between the parking lot and the curb of the main road, it's just grass there, with no fence. If you happen to be staying in the Casitas area, by walking through the convention center, and then across the parking lot, you would probably be able to shorten the walk by at least 1/3 of a mile.