The other day I asked for an analysis or at least an UML diagram since we are having quite some troubles and my boss looked disgusted at me for asking such a question. I’m not a professional backend developer, so I don’t know how it works professionally
I have no idea what you mean when you say you found an error in the design that says it was an INSERT instead of a SELECT.
If you are relying on a design doc with SQL in it, that’s a massive waste of time.
How many tables are in the schema? Have you reviewed them? Are there any naming conventions being followed, or is everything inconsistently named? Are there specific cases where tables are not normalized properly that you can ask specific questions about why they are that way? If the person that designed the schema is making “trivial” mistakes, there’s no reason to expect that stuff that doesn’t make sense to you will be something they intentionally did.
I guess what I’m saying is, you need to do some due diligence and survey the schema and write down some specific questions and that may lead to writing a UML or other doc to identify errors, but it doesn’t sound like you’ve done that.