Just take one step at a time before talking about NCAT. You will have to see what findings and recommendations come from your report and if you and your inspector are of the opinion that it is an OC issue with waterproofing, then present your report to the committee, and perhaps have your inspector address them at a meeting, which may be more $$ for you to bear for his attendance. The committee may get second and third opinions of their own. The silly season is almost upon us, and I don’t expect much will be done to further your issue until well into next year.
The complex being 12 years old is not really all that old, and there are second had tile yards with boxes of excess tiles that can be matched to your current ones out there somewhere. It’ can be a fun project for a person with some time on their hands to go rummaging through cartons. I’ve done it myself with tremendous results. Don’t forget to take a photo of you present tiles so the staff can assist to send you in the right direction.