I agree with struggler, a special levy or even a levy increase can’t just be imposed by the EC or even the OC. I think it requires a vote with not less than 25% of those voting against the levy/special levy.
It is a matter of who will support the levy. When you say “We have supplied professional quality artworks” I am not sure whether you are saying just yourself or various owners. If the supplied artworks are “very much admired by every other strata occupier” perhaps it wouldn’t be too hard to get other owners to vote against the levy.
Knowing how most owners hate levy increases and special levys pointing out to other owners that they are paying for something that you all now get ‘for free’ has to be a strong argument for not replacing the paintings. As for the flag pole the same rules apply, how many want it and are willing to pay for it?
As for the legalities, acquistion of the photos and flag pole would not be authorised from the Admin fund, refer section 68 and 75(1) of STRATA SCHEMES MANAGEMENT ACT 1996. This is because the expenditure is not recurrent. The expenditure probably could be authorised under sections 71 and 75(2)(a) as acquistion of personal property.