Its annual report for last year showed the organisation had revenue growth of 16.3 per cent.
But sources within the tribe say the appointments of the three, who have influence over TGH direction and strategy, could be a step backwards.
Former tribal heavyweight Tukoroirangi Morgan raised concerns about the appointments.
Both Mr Rau, who was chief executive of Tainui's administration arm, Waikato-Tainui Te Kauhanganui Inc, and Mr Wilson, a former member of Te Arataura, were dumped from their respective positions within a week of each other in 2009 for alleged breaches of confidentiality.
Mr Wilson was later reinstated because Te Arataura did not have the mandate to remove him, but Mr Rau took his case to the Employment Court and lost.
Mr Rau returned to the tribal leadership last year after his marae, Te Kotahitanga, voted to make him one of its representatives on the tribal parliament Te Kauhanganui.
Mr Morgan said Mr Rawiri had corporate experience "but the other two don't, so I have a major concern".
"At the hub of my concern is confidentiality of information."
Mr Rau said Mr Morgan was entitled to his opinions, but would not comment on them.
"I was a director of TGH before so it's not my first term," he said.
He said he had experience managing the iwi's commercial fishing company while Mr Rawiri was on the Fisheries Commission and had "a lot to offer".
Mr Rau said Mr Wilson did not have a commercial background but had a strong social conscience.
Te Arataura chairman Tom Roa said he was comfortable with the election of Mr Rau and Mr Wilson.
He said the allegations against the pair of breaches of confidentiality were never substantiated.
Sir Henry van der Heyden has been appointed as a director to the board, replacing the outgoing chairman, John Spencer. TGH's new chairman is expected to be elected next month.
