Tbh, at some point I was also thinking maybe I should avoid calibrating elevated portions of roads, due to the inherent "transformation" that may or may not exist for satellite imageries.

But then the unexplained space between HKU Main Building and Pok Fu Lam Road is too obvious. And the old shape seems inconsistent with the sidewalk shapes.

As long as it is still mostly accurate, then it should be ok. No point in pursuing 100% accuracy: even satellite coordinates might shift slightly every once in a while, and then we will all be building houses on sands. When it looks nice (ie shape form, relative positioning, etc), and is mostly accurate, then it is a good map.