"However, as soon as the accounting is current, then I can properly track sales tax liability and the payment using QB sales tax tool and trust the data is correct."

Get a copy of their Sales Tax filings for that same timeframe. Now you can see what they reported for Sales, taxable and nontaxable gross, and what they reported they accumulated as owed for sales taxes.

Remember that Banking is not giving the whole picture: spending doesn't equal expense. Expenditures from bank include loan debt balance payment amounts, investment in new assets, owner draws or shareholder distributions, and other uses of funds that are not considered expense, including sales tax and payroll tax liability. The same is true of deposits: inflow does not equal income. Inflow and outflow are processed. Expense, Sales, Income, Equity, borrowing, etc are the activities or why the money is flowing.