Authorities stopped monitoring Faith and no checks were made to confirm the family had returned to New Zealand.
Faith's maternal grandfather Paulo Leaso told the Bay of Plenty Times that Faith had not been at school for eight months and neither the school or social workers found out what was happening.
"I think that's the most important thing so this can't happen again, the school and social workers must find out what has happened to someone like Faith."
Mr Leaso said the lack of financial help for New Zealanders living in Australia may have been a contributing factor to his granddaughter's death.
"I want them to change that part of what happened to my daughter, because she went to apply for money but they said no because she is a New Zealander, not Australian.
"The money went to the husband and he used the money on something else. The wife is supposed to get the things for the kids. It's not fair.
"That's a reason maybe why my daughter ... something happened to her mind."
Mr Leaso said he wanted Australian agencies dealing with children and parents to make sure they did their jobs properly. "Especially a New Zealand woman married to an Australian. I think it's very silly to let the man take all the money. I'm very appreciative of New Zealand for looking after their people.
"Social workers should do what they are paid to do and make sure if Faith doesn't come to school for two days, then find out where she is gone. In New Zealand they are very good like that."
Mr Leaso had not been able to speak to his daughter since she had been imprisoned in July last year.
She was sentenced to seven years for manslaughter.
Her husband also pleaded guilty to manslaughter and was sentenced to three years behind bars for turning a blind eye to the abuse.
The heartbreaking case highlights failures within the Australian child safety network, Queensland coroner Jane Bentley said.
She said communication breakdowns between state and federal departments, as well as external agencies, were a significant factor in Faith's death.
- Additional reporting Herald on Sunday