Defence lawyer Virginia Pearson said it was "opportunist" offending by an intoxicated teenager who had accepted responsibility at the earliest time.
"He was asked to assist in putting the fire out. He is very mindful this could have been a serious incident. It was an error of judgment - out of character for him," she said.
Rongonui was willing to make changes, Ms Pearson told the court.
"He does have ambitions."
Crown Prosecutor Ms Light said the offending was at the lower end "for that type of offending" as she recommended the judge order supervision for Rongonui to "address the underlying issues" which had lead to the crimes being committed.
Judge Harrop told Rongonui the victim of the arson would have been afraid and those he stole from were also left distressed including an 80-year-old man who had the business documents stolen, and the owner of the "prized" tae kwon do belt.
"The mental consequences were quite significant ... at the time it was distressing ... you did not set out to cause mental anguish but this is what happens."
He noted Rongonui was well supported by his family.
"You are undoubtedly of good character. Your whanau is close and supportive. That gives me confidence you will learn your lesson."
The judge sentenced Rongonui to 100 hours' community work on the arson charge, along with 12 months supervision and ordered he pay reparation of $130 at $10 weekly.
On the burglary and theft charges Rongonui was sentenced to 80 hours' and 40 hours' community work to be served concurrently with the 100 hours on the arson charge.