I think you may be coming at this from slightly the wrong angle. The owners corp (you and the other owners) should be having a defects survey done and then making an official claim against the developer.
He has no legal responsibility to go looking for defects. But if you find them – major defects withing six years and non-major within two – he has a duty to fix them at his expense.
By the way, “non-major” is basically anything that is a defect but doesn’t mean the block or any part of it is uninhabitable.
Get a professional defects survey done before it is too late then present that to the developer along with a statement of claim.