Another matter to determine is when the building was erected.
In many high rises buildings, sliding doors were in place when built which allowed for a balcony.
Some proprietors over time enclosed the balcony by moving the sliding doors forward.
It is my understanding that in pre 1972 (or so) buildings (regardless of when the balcony was enclosed) that the original sliding doors and the sliding doors which replaced the original ones remain “owned” by the Owners’ Corp but repairs and maintenance is for the a/c of the lot owner.
This is proven by the fact that in many cases the OC will tell a lot owner who can perform the works and what the specifications are to be.