The Scottish Hospitals Inquiry, which has been looking at the planning, design, construction and maintenance of hospitals, is hearing final submissions before publishing a report later this year.
It was prompted by concern about patient safety following a series of infections and several deaths, including that of 10-year-old Milly Main.
The inquiry will hear closing statements from the families later on Thursday.
On Wednesday, the chair of the inquiry, Lord Brodie, asked why the health board had changed its position after alleging unprofessionalism and malevolence on the part of the medics who raised concerns.
The health board’s lawyer, Peter Gray, acknowledged that several criticisms made about the whistleblowers were neither helpful nor fair.
He said the people running the hospital should not be criticised as the failure to listen to the whistleblowers was an organisational failure, adding that changes have since been made.
Earlier this week, Scottish Labour leader Anas Sarwar called for First Minister John Swinney and former First Minister Nicola Sturgeon to be investigated over failures at the hospital.
NHSGGC has already been named by prosecutors in a corporate homicide probe which is looking into the deaths of Milly Main, two other children and a 73-year-old woman at the hospital campus.
The death of Molly Cuddihy last year is also being investigated by the Crown Office.