Efforts to reclaim the hundreds of millions of missing dollars and bring those responsible to justice have proved problematic.
As of the end of August, $128.3 million in cash had been recovered. Nearly 40% of that came from normal customers, the report says, even though they represented only 8% of the loan balance of the bank when it went into receivership.
Kos and the other authors also criticized Afghan authorities' efforts to investigate and prosecute the case.
"There has been clear and direct interference with the criminal process by high-ranking officials that goes so far as to identify who should, and who should not, be indicted for criminal conduct," it said.
"The lack of action from the Attorney General's Office also because of political influence has resulted in a lack of investigation, procedural delays that have allowed perpetrators to escape and likely for money derived from Kabul Bank to be lost forever," the report says.
The Attorney General's Office didn't respond to calls seeking comment Wednesday.
The report's authors also appear to be unimpressed with the actions of a special tribunal set up to deal with the case of Kabul Bank.
"The tribunal appears to have been engaged in everything else except the processing of the one case they have before it, contrary to the most basic principles and laws related to fundamental justice," the report says. "Even the recent criminal proceedings at the tribunal do not wholly satisfy concerns about whether justice will prevail in the Kabul Bank case."
The report concludes with a stark warning: "If the systemic issues raised by Kabul Bank are not resolved, the viability of Afghanistan as a fully functioning democracy is lost."