Clearly there is no objection, per se, to air cons in the building – as some owners already have them.
However, it is reasonable to have a by-law that protects architectural standards. So, if, as you say, the location of your proposed condenser does not breach the architectural standard then the new by-law will not apply. And I do not think that any by-law can just ban air cons for the sake of it.
So take photos of your balcony for later proof if needed. And don’t forget, NCAT have already ruled that it is okay to have an air con installed under the condition that architectural standard applies.