If you don't understand the code, how can you know if it's good enough?
I guess you could ask the model. "Yes well done, you're a visionary software engineer".
Who cares if it's good enough? Send the product, if people use it, it's good enough. If not, let users debut it and give "feedback", problem solved. You then advocate to these users, make them feel important, make them your cash cows, rinse and repeat.
Every team I have been on have been more successful when they gave up on the product ideals and just ensured that the customers were hooked and satisfied.
I've been experimenting with vibe-coding some games. One of the games started performing very badly in a particular menu, and I began suspecting it's because of a shader that may be redundantly computed way too much on too many large surfaces. I began writing my suspicion to Claude, then stopped and decided to just describe the problem and see if it would come to the same conclusion as me. A few minutes later, it had profiled the game, found what contributed most to the poor performance, fixed the rendering and made the game performant again. I didn't have to inspect the code to do any of that. The current models (paired with coding harnesses) love to test and validate their results by running the games, taking screenshots, singling out individual parts, including logs to reproduce errors or other issues, and they love to create tests. The code is good enough in the same sense that the code I used to write was good enough if it did what we wanted. My non-technical bosses didn't have to inspect my code for that.