Update Combo Chart Title Dynamically

I have a combo chart, but I couldn't change the title of the combo chart dynamically, but when I change the chart to a column chart or line chart, the title successfully changes but not with the combo chart.

Here is the code I used to change the title dynamically

function myFunction() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var newtitle = sheet.getRange(7, 2).getValue();

  var charts = sheet.getCharts()[3];
  var chart = charts.modify()
    .setOption('title', newtitle)
    .build()
  sheet.updateChart(chart)

}

The title of the chart will change depending on the text written/chosen from var newtitle = sheet.getRange(7, 2).getValue();

Hope someone can help with the code. Thank you in advance

In my experience, unfortunately, it seemed that the title cannot be directly changed. When your showing script is run, an error like Exception: Service Spreadsheets failed while accessing document with id ###. occurs. So, in my case, I used a workaround. How about the following workaround?

Sample script:

Before you use this script, please enable Sheets API at Advanced Google services.

function myFunction() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getActiveSheet();
  var newtitle = sheet.getRange(7, 2).getValue();
  var chart = sheet.getCharts()[3]; // 4th chart in the active sheet is used.
  var chartId = chart.getChartId();
  var chartObj = Sheets.Spreadsheets.get(ss.getId(), { ranges: [sheet.getSheetName()], fields: "sheets.charts" }).sheets[0].charts.find(c => c.chartId == chartId);
  var series = chartObj.spec.basicChart.series.reduce((o, { type }, i) => (o[i] = { type }, o), {});
  var updatedChart = chart.modify().setOption('title', newtitle).setOption('series', series).build();
  sheet.updateChart(updatedChart);
}

• When this script is run, the title of the combo chart of var chart = sheet.getCharts()[3] is changed.

Note:

• This is my workaround. I think that there might also be other approaches. So, this is just one workaround.

Added:

As another approach, how about modifying the title using Sheets API as follows?

function myFunction2() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var ssId = ss.getId();
  var sheet = ss.getActiveSheet();
  var newtitle = sheet.getRange(7, 2).getValue();
  var chart = sheet.getCharts()[3]; // 4th chart in the active sheet is used.
  var chartId = chart.getChartId();
  var { spec } = Sheets.Spreadsheets.get(ssId, { ranges: [sheet.getSheetName()], fields: "sheets.charts" }).sheets[0].charts.find(c => c.chartId == chartId);
  spec.title = newtitle;
  Sheets.Spreadsheets.batchUpdate({ requests: [{ updateChartSpec: { chartId, spec } }] }, ssId);
}