Man, although your intention is good, but I believe the OP had enough of it.Your lawyer is incompetent and can't believe you're still using them. Your bed to lie in.
Actually what he submitted may work, I read some posts in a thread that people forgot to disclose their prior refusal VISA history on the application and received the procedure fairness letter, and then they replied as the way the OP replied, and IRCC accepted the explanations.
So, be understood, applicants are humans, and do make honorable mistakes. I mistakenly checked a wrong box on my application draft, then fortunately I found out and corrected it on my final application. It happens.