High rise plumbing problem
I lived in a 10th floor apartment and had repeated floodstoilet over flowed multiple times and water would always fill up to the top before it went down. We never had stuff in the toilet. Eventually it was replaced and was fine for a few months. Then in the middle of the night a connection hose from wall to toilet started spraying so much water that the apartment was filled with 4 inches of water. The super said it was because of the flap(we never had a flap or running water problem ever and we were fast asleep)
The sink would repeatedly flood with black water and things from upstairs neigbors(bone- we are vegetarian) would come out of our sink. Never once was there anything of ours found and they used to have the people above us turn off their sinks in order to fix ours.
My belief if that there is something intergrally wrong with the plumbing- have you heard of anything like this before?
I believe the plumbing in the building was faulty

I don't know if I would say it was "faulty". What you are seeing is not uncommon in high rises. Typical to apartments is common drain systems. 1 drain for every 4-6 units and then into a larger common drain. The drain below you gets blocked and then it overflows your toilet. Not much you can do about that. Sounds like some of your upper neighbors have bad disposal habits with bones in the plumbing. I would suggest a supers discussion with tenants as to what may be drain discarded.

I agree with the above post. The problem is "building's" problem, not yours. You should bring it up to the Building Management and ask them to deal with this problem in timely matter as this will most-likely occur again.

The burst toilet water supply line was an accident. Here I suggest to do visual inspection on your water lines and angle stops. If you see signs of corrosion or calcification, replace them.

Milo