Crown solicitors had argued the sentence should have been 15-16 years and that the minimum non-parole period should have been at least half.
It was thought to be the first slavery trial in New Zealand and included evidence that victims, often members of Matamata's extended family, had been brought to New Zealand under promise of a better lifestyle and chances to send money back home to family in Samoa.
Complainants gave evidence with various allegations not being paid, working for unreasonable hours, being made to do chores at the Camberley home of the contractor, being assaulted, and being confined.
In one case Matamata had traced a transgressor who fled to Auckland and ensured his return to Hawke's Bay.
The judges said in the decision it was accepted that a minimum non-parole term could not be applied for the slavery offences, but accepted in relation to the trafficking detail that the threshold had to be higher "because the court had to be satisfied at that time that the circumstances took the offending out of the ordinary range of offending of the particular kind."
"We think Mr Matamata's culpability was sufficiently high, having regard to the scale and duration of the offending to make the jurisdiction available," the Judges said.
"This aspect of the appeal caused us some difficulty," they said. "We are reluctant to impose a minimum period when the trial judge did not think it necessary."
Noting the judge's reference to Matamata's age, the appeal judges said: "We agree he is at low risk of reoffending, although he remains intransigent and in our opinion his risk is low, because he is unlikely to get the opportunity."
They accepted Crown submissions that general deterrence and accountability were important considerations in offending of the type and that they "apply with considerable force" in this case.
Matamata's offending was "calculated commercial offending on a large scale and over a long period of time," they said.
"He derived his power from misuse of his trusted status and the serious and sustained abuse of the many victims," they said.
As part of the original; sentence, Matamata paid $183,000 in reparation to complainants, from sale of his interest in a Camberley home where some of the offending was committed.