I think Allen has you on the right track. If you are trying to alleviate your concerns about potential future problems with your construction project by modifying the terms of your current warranty, the wording is probably critical to achieving that goal. That's if your builder is even willing to modify the terms now, which would be a miracle in and of itself. Why should he? Why would he? Even if you're only trying to get him to provide some additional written agreement, separate from the actual contract, to better define the existing warranty, I'm not sure how legally binding that would be. I think it would have to be a more official amendment to the contract to have real value.
Keep in mind that making the warranty more specific, however it's done, might have the opposite effect of what you're after. By that I mean, phrases like "If any of these issues occur XXX, YYY, ZZZ..." might negate the warranty from covering issues AAA, BBB, CCC if they occur instead. You might be better off with a more all-encompassing general statement, something that includes terms like "standards and practices" or the like. And that's something probably only a qualified NC construction attorney, with experience in litigating such things, could properly formulate. Or that same attorney could confirm that the wording in your current warranty already covers that.
Possible Alternatives
Was your pool engineered? Are there any engineering specs for the gunite? I ask because you could potentially use those specs, along with a proper core sample test, to find out now if the gunite was properly installed. I'd be floored if those specs existed, let alone were part of your contract, because residential contractors just don't generally provide such things. And the testing/coring is not a simple thing. But it is done. It is a thing. (Just not generally with pool construction.)
Or you could call in a third-party expert (typically another pool builder) to evaluate your gunite for proper installation. That's if you could find a local guy that's willing to potentially bad mouth another local guy.
Keep in mind that those two alternatives, or anything else you do that communicates your lack of confidence with the builder, or hints at potential future litigation, might only serve to get you less pool than you'd get otherwise. Nobody likes somebody looking over their shoulder (even if it's justified). And it could serve to impact the builder's enthusiasm to do a first-class job (even if subliminally).
What you're seeking is not unreasonable, it's just not particularly realistic to expect it can happen after you've signed a contract. But given the six figures you're probably investing, it might be worth three figures to get some assurances from a construction attorney. Your best-case scenario is that the current wording in the warranty already has you covered.
