You have recently completed "fix the Profit and Loss report via the API to support periods and timeframe", but not for Balance Sheet.

This means can't do weekly cashflow reporting as balance sheet items are end of the month only which defeats the purpose of the P&L fix as need to balance this across to the balance sheet.

Should be able to do as at any date.

BUT can do this report via the Xero Reports in Xero. Needs to be consistent.