Let me ask an incendiary question (I feel not great that I even have to qualify this, but I'm admittedly nervous of talking about these sorts of issues in certain lights given social context nowadays); but you're clearly thinking about this comprehensively enough that I'm curious to hear your thoughts, I don't necessarily have an answer either.
Is some amount of inequality at scale _necessarily_ a bad thing, if it arises from a fundamental systemic property of the socio/business/economy context we've bought into? I'll make a rather absurd parallel; look at money itself. To have more money enables gaining more with less effort, (citing the common "boots" theory of economics, basic laws of investing returns, etc) Therefore, enabling anyone to have more money than someone else creates significantly compounding inequality. Should we ensure that can't happen? I acknowlege it's a bit of a strawman but I would hope it also conveys a point both of implicit systemic cycles and tradeoffs of redressing them. As you concede, there's a tangible benefit towards hiring known entities and cohesive teams, even though at scale it tends to favor the incumbent majority.
Rather than ask if the inequality is in itself bad, I'd try to look at the funnel and see if there are any truly improper barriers to the out-group, and focus on rectifying those. Like in CS I'm always wary of KPI based iteration since it can cause "overfitting"/ignoring transitive effects, and "raw diversity numbers" to me is a very opaque KPI.
(Whether the systems that lead to these patterns is good is a totally separate discussion and one so huge I don't think I have the background to speak on it well, but I'm trying to question pragmatic steps to be taken that don't involve a burn-it-down-and-rebuild or throwing the baby out with the bathwater)