I hate to have to say it but some buildings are just badly built. It is unfortunate that you have purchased in a building that has not got good insulation.
I live in QLD where some of the older buildings along the waterways that were not ever originally built as residential buildings have been turned from industrial or commercial buildings into residential buildings. Noise issues are unfortunately common place.
There isn’t much that you can do if the council have deemed the building to be compliant.
You can’t prevent people from using their apartments either to walk around in or from hosting a gathering as long as they are within the normal permissible hours.
If the building has been poorly insulated then a noisy owner or tenant can cause just as much noise as a short term airbnb tenant … at least the ‘noisy’ short term tenant only stays a short time whereas a noisy owner can be there for very much longer!
You could install a dropped ceiling with sound insulation in your own apartment which may assist in reducing the noise issues.
Good quality ear plugs are however, a cheaper option.