I wouldn't call it theft, exactly. Presumably work did get done. If I'm reading it right, its just a terrible conflict of interest. The board uses donations to pay companies to work on LibreOffice. That seems totally fine. Some of the board were running/part of companies that rely and work on LibreOffice. That also seems mostly fine? You want your board to represent your community. Then, those same board members directed work towards their companies.
That's definitely a conflict of interest, but I wouldn't call it theft unless you prove the foundation was getting a bad deal. Could the foundation have gotten the work done better or cheaper hiring non-represented companies? That's the question you have to answer to call this theft.
It doesn't seem that is really what the foundation is arguing though, so I'm guessing it wasn't that bad. It seems more their argument is that this violates the non-profit laws they operate under.