I concur that "damning" is not really a curse term With this context, but merely usually means "leading to condemnation" and so just isn't inappropriate in alone in formal writing. I've certainly heard of "essentially the most damning proof", generally in reference to evidence of a serious criminal offense, and https://raymondhbdrs.blogdigy.com/the-basic-principles-of-marketing-case-study-solution-58010946