Hello again.
This is a rather difficult part of the task.
Tall buildings need a specific approach to map.
But, your mappings are not that accurate as well.
You collected several buildings and mapped them as 1 building.
Not accurate mapped and squared. 
you also included not build areas in a building
As I said, a difficult part. 
Please find a what easier task to start with.
Best regards and keep mapping
            ---
            
            Published using OSMCha: https://osmcha.org/changesets/133512897
            