This is all things I noticed from the first version, better posting now than not at all.
Jumping on top of the crates outside of blu's spawn, red could see everything they were doing, I'm assuming it's a nodraw issue.
Add cover to the area right outside of blu spawn, right now it's basically a killing field. Uber heavy/demo > any defense in that area.
Give the defenders more cover on A. As of the test attackers could spam to their heart's content out that window, and red really had no where to hide from it.
SIGHTLINE IS HUGE. Snipers win. Everyone else loses. Also, he only real viable engie spot here was that little indented room down to the right of this pic.
The last point suffers from an amplified version of the problem at C. The attackers have only one, really good route to go, and the defenders have a really bad open area to defend. If the team I was on had actually pushed together and timed our ubers, we could've wiped through all of the sentries they had built under this loft.
Now, presented through the eyes of the supersandvich death cam, is a suggestion. Add somewhere above the point easily accessible for defenders.. The last point is supposed to be hard, give the defenders an a bit of help besides their spawn being nearby. How it's done doesn't really matter. extend the current overhang, add a new area across from it, completely rework the area, whatever. Make it so the defenders have more options than waiting for more people to drop down from above.