The 62-year-old, from South Africa, faced six charges of accessing a computer for dishonest purposes after he misrepresented the transactions in company documents as payments to creditors.
Justice Asher reserved his decision on Jackson's appeal, but not before warning him his original sentence could have potentially been more severe.
"I took that money, I'm very sorry for doing that. It was a stupid mistake," Jackson, appearing via video-link from prison, told the court this week.
"I want to set the record straight that a lot of facts given by the complainants to make me look worse than I was were totally fabricated.
"I know ... what I did was stupid and $570,000 is a lot of money.
"I'm the one who's come out with nothing. I've been declared bankrupt, imprisoned, my family has suffered [and] now immigration want to deport me back to a country where I've got nothing and nobody.
"If the court says the [original] sentence is just and fair, I accept that. If they don't and they want to reduce the sentence, well and good.
"But, your honour, I just wanted to put my facts, which I feel are the true facts, forward to the court."
Some of the facts Jackson disputed included whether one couple who were victims were able to afford a house after the business collapsed.
He also said of that couple that the "money wasn't theirs to start with, it was owned by the company".
Justice Asher said: "[Your sentence] seems to me, Mr Jackson, to be very modest given that you have been found guilty of taking over half a million dollars, which is never going to be given back to these people.
"I'm not going to increase it but I'm just letting you know that I do have a bit of trouble with it. It seems quite low to me."
He will make his decision at a later date.