So I was exploring the garden and I found a way to get outside legit. Right when u cross the portal, look for the statue on the right. There is a stone ledge under the arm on your right. Hop on that, and turn to your left, you should see the sky. Do some pro parkour, and your on top of the Black garden! Have fun exploring. EDIT: once you are on top of the garden, the entire structure might not be fully generated. Just wipe a few times or give it a bit