Thanks for correcting!
I had same exact problem with somewhat similar "air corridor" here: https://www.openstreetmap.org/way/475617182

I fixed it in a similar way, as you explained. 

I still fill a bit confused regarding path underneath. Once I extended building and added building part, path had warnings. I think (but not really sure for now) that warning gone away once I placed points of separation of the path (for `covered=yes`) onto the contour of the building. But I'll figure this out.

Thanks again for you guidance!