It's also worth pointing out that the nature of the green card interview is largely up to how the interviewer feels about you. It's a terrifyingly subjective experience.
There was an error in my wife's green card application that many people (including myself and our lawyer) should have caught. Our lawyer promised us that during the final interview this could be trivially corrected on the spot. Despite many smiles and laughs during the interview it's clear the interviewer didn't approve of how my current wife and I met (it involved a divorce) and so he decided that he couldn't possibly correct the error during the interview, and that while we passed, we would need to wait nearly a year for the correction.
While this was frustrating the interviewer could have just as easily decided, at his discretion, that our marriage was not "real" (despite the fact that the reason for his objection was ample evidence that it was quite real), so it was a pain we had to suffer. I've spent enough time working with petty bureaucrats to know it's better to accept whatever means they try to prove their own power than to fight it.
Is it possible your lawyer was just wrong when he told you that?
Like the interpretation of the situation seems to hinge on that, because if we didn’t know that it was usually fixed on the spot, then it could very well just be protocol to go through a correction process that takes awhile (for other dumb reasons but not because someone was wronging you personally).
Errors happens on immigration forms all the time. Many of them aren't a big deal and can be corrected but there's a right and wrong way to do it. Fixable errors include things like failing to mention all your employers that you worked unauthorized or your name having a different spelling in certain cases. Since unauthorized work is forgiven if marrying a US citizen, the omission of employment is a correctable error.
The right way to fix this is to type out the questions you want to correct into a document (called an errata sheet) with the corrected answers and to hand that to the visa officer with your ID at the start of the interview. The reason you want to do this is you want a paper record that you volunteered this information. Anything verbal can be argued that you only revealed such information when confronted and that's a problem.
So I don't know what your issue was. Errors with a divorce could be as serious as you weren't free to marry because at the time you got married your divorce wasn't finalized and that invalidates your entire petition and there's no correcting that.
Another big one is USCIS not believing your divorce is real. this happens if you get divorced in certain countries (eg Ghana, Nigeria) where apparently fradulent divorce decrees are a real problem.
It had nothing whatsoever to do with the divorce itself, I'm a US citizen and was (legally) divorced for several years before the interview (and my marriage). The error was a typo that the interviewer was informed about well in advance of our interview, and could have been corrected by changing a value in a field which our lawyer informed us had been done many times in the past for other couples.
There was an error in my wife's green card application that many people (including myself and our lawyer) should have caught. Our lawyer promised us that during the final interview this could be trivially corrected on the spot. Despite many smiles and laughs during the interview it's clear the interviewer didn't approve of how my current wife and I met (it involved a divorce) and so he decided that he couldn't possibly correct the error during the interview, and that while we passed, we would need to wait nearly a year for the correction.
While this was frustrating the interviewer could have just as easily decided, at his discretion, that our marriage was not "real" (despite the fact that the reason for his objection was ample evidence that it was quite real), so it was a pain we had to suffer. I've spent enough time working with petty bureaucrats to know it's better to accept whatever means they try to prove their own power than to fight it.