I don't even like OpenAI, but HuggingFace is free to sue or not sue OpenAI for the breach - and also to wring whatever concessions they can out of OpenAI behind closed doors in exchange for not suing them. And if the mere possibility of legal action was enough for the parties to resolve their conflict amicably? Then the law has served its purpose.
Any investigation into this matter is going to be political because the outcome of the investigation is very likely to effect all of human kind. Unless you're some kind of special outside investigator outside of a governor or the presidents control the findings that you turn in are very much going to have the finger of elected officials tipping the balance one way or another. For the average rank and file the only winning move is not to play.