Your Strata Manager may be of the opinion that IF the balconies form part of the Lot/s and are not Common Property, then the responsibility for the maintenance and repair of the grouting and tiles is the Proprietors' responsibility.
In the absence of any Special By-Laws that your Plan may have to the contrary, the maintenance and repair of the original floor tiles is the responsibility of the Owners Corporation; just like those on other floors within the Lot.