Hello. Thanks for mapping on this task.
Please square each rectangular building with the Q key.
mapping of tall buildings differs from standard buildings. Because the imagery is taken at an angle, you see both the roof lines and also the side of a building. How do you map such a building? Map over the roof lines and lastly slide the mapped building to the footprint. Here is a video how that is done.

https://drive.google.com/file/d/1V5-bADsYiffCD9bo6l64YOdTvmKqMGry/view?usp=share_link

Best regards.