Taking a different approach, this example works for copying the value. So it should get me what I need, but I'd still like to know if there is a way to get the count of rows for a given variable or named range if possible.
In this example my timestamp is the first column, and epoch is the second column. I have headers above the named ranges, so it starts at row 1. This also assumes that the 'Date__EPOCH' range is empty when post processing starts.
ExcelReportUtility.openNamedRange('Date__EPOCH', false); var timestamp = null; var i = 1; do { timestamp = ExcelReportUtility.getString(0, 0, i); if (timestamp == null) { break; } ExcelReportUtility.writeStringToNamedRange('Date__EPOCH', timestamp); i += 1; }while (timestamp != null);