The first article had several links associated with it, including peer reviewed articles. I am not sure why you glossed over that. For example, one links to another, which cites the source as a 2022 paper in the Journal of Academy of Management, (abstract). Another is written by BCG and another by McKinsey, and while not up to the peer reviewed standard, they operate in this segment and have some expertise. The analog would be similar to listening to Dr. Offit or Fauci about their recommendation on how to navigate a pandemic with a novel virus without having direct expertise on the matter. Sure it is an appeal to authority to some degree, but that authority has credentials. And being a lawyer, you often cite cases which is just the opinion of some subjective people, not exactly a higher standard. Heck, so many of them are wrong but they just defer to the other guy who said something. Your SCOTUS is littered with historical idiocy and corruption.
BTW I knew you you latch on to that one. IIRC, the issue was that the study didn't differentiate between DEI as a platitude and DEI as a company culture commitment which in one of the other sources linked, discussed this aspect in greater detail. And yet, they still found to some degree a positive correlation, had they had a slightly more robust study, they would have segmented the data into categories and then analyzed it and included the statistical output so we could see the null hypothesis results.
The diversity programs failing HBR is a little dated and narrow in its focus. While it is true the video for new employees and subsequent testing method is not a great initiative and does little to impact the culture of an organization, that doesn't mean that a cultural change within the organization will have the same impact. The interesting aspect of that article was the lawsuits paid out for harassment claims, and they should have looked into the rates in which those maintained, increased or decreased through time and awareness. What are included in the previous links are surveys on employee engagement, reduction in turnover, financial performance gains, some of which is linked to expansion into new markets based on diversity. Of course this could also be bad, if they just know better neighborhoods to dump toxic chemicals into.