
I agree if the expectation was for people to wear black only, then the text of the code should have said “black” and not “dark.”
Formal Dress Codes suck, but at the least the events are usually short and you can at least take off the tie and jacket, maybe roll up the shirt sleeves if they’re long.
Unless there is a Dress Code that explicitly says you must wear a “black” suit, you’re fine. I wouldn’t worry about it.