You may be better off netting your balcony. I have a unit where most rooms open with sliding doors to the large balcony which runs the full length of the unit. I wanted my grandchildren to be safe and it is impractical to keep them inside . We moved from Hong Kong where most families installed netting on the balcony with young children and thought this would be easy. My owners corporation had no problem with it as you hardly see it, It is black netting. The hard part was getting it. I eventually ordered it from Hong Kong but I just googled now and there are firms that now do it in Sydney.
I think there was an NCAT case about safety netting a couple of years ago so there may even be a precedent for you to use on the committee. You can always argue that the net protects people below from toys and other projectiles from the balcony!
Good luck. It is really annoying that people put obstacles in the way of children’s safety. If it were a work site they would be compelled to do it!!