So, to explain, i simply merged the north-eastern corner and the north-west corner of the building=* and the building:part=* together.
I then added node on the left side of this area Way: 1174306437 | OpenStreetMap where it intersects with Way: 1174306435 | OpenStreetMap this area and where these two intersected i merged the node as well with Node: 1359856323 | OpenStreetMap this point.
For a ‘why not’ i also marked the tower circles and pressed O so they get in a perfect circle 
I think this should solve the problems with the renderer - i hope i did not miss something.
EDIT: I was about to post like “If you want to check, some showed a nice renderer for individual building some time ago” and while looking for it i found its your tool lol All new 3D rendering ... an "OSM Building Inspector"
Seems to not work btw. - tried with firefox, chromium and edge. Far away render with no possibility to change view.
EDIT2: Found the other one OpenStreetMap Building 3D Render by @Beakerboy GitHub - Beakerboy/OSMBuilding: render an individual OSM building
Two cool projects!