Stimulsoft provides a native Blazor designer; assigning a report and handling its save event lets users edit and persist templates.

Place the designer.
<StiBlazorDesigner Report="@Report" OnSaveReport="OnSaveReport" />
Persist on save.
private void OnSaveReport(StiSaveReportEventArgs args)
{
    var reportJson = args.Report.SaveToJsonString();
    // store reportJson where you need
}

How it works. The designer edits the bound report in the browser and raises OnSaveReport when the user saves, so you control where the template goes.
На скриншоте ниже Вы можете увидеть результат выполнения данного кода:

Editing a Report Template in the Designer