I'm having trouble putting data from a custom dialog into a specific range in the sheet, like this:

Everytime i enter new data in the dialog, it should append a new row in that particular range. So far i'm using appendRow for that matter but the problem with that is that appendRow counts in ALL columns in the sheet, so that i'm having blank cells in the particular range, like this:

This is one of the codes i'm using :

//STUNDE EINTRAGEN VIA START
function showDialogKBSTART() {

  gotoSheetSchueler();

  var widget = HtmlService.createHtmlOutputFromFile("formKBSTART.html").setHeight(450).setWidth(450);
  
  SpreadsheetApp.getUi().showModalDialog(widget, "Stunde eintragen");
}

function appendRowFromFormSubmitKBSTART(formKBSTART) {
  
  SpreadsheetApp.getActiveSheet()
    .appendRow([formKBSTART.Datum, formKBSTART.Inhalt, formKBSTART.Sozialform, formKBSTART.Dauer, formKBSTART.Lehrkraft,, formKBSTART.Ausfall]);
  SpreadsheetApp.getActiveSpreadsheet().getSheetByName('KlassenbuchGesamt')
    .appendRow([SpreadsheetApp.getActiveSheet().getName(), formKBSTART.Datum, formKBSTART.Inhalt, formKBSTART.Sozialform, formKBSTART.Dauer, formKBSTART.Lehrkraft, formKBSTART.Ausfall]);

  SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getRange("A9:A").setNumberFormat("dd.MM.yyyy");
  SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getRange("A9:F").sort({column: 1, ascending: false});

  SpreadsheetApp.getActiveSpreadsheet().getSheetByName('KlassenbuchGesamt').getRange("B2:B").setNumberFormat("dd.MM.yyyy");
  SpreadsheetApp.getActiveSpreadsheet().getSheetByName('KlassenbuchGesamt').getRange("A2:G").sort({column: 2, ascending: false});

      Utilities.sleep(500);

  SpreadsheetApp.getActiveSpreadsheet().toast("Stunde eingetragen!","