A custom font can be registered with the engine so the dashboard renders and exports with it.

In Angular.
import { Component } from "@angular/core";
import { Designer, Stimulsoft } from "stimulsoft-dashboards-js-angular/designer";

@Component({
    imports: [Designer],
    template: `<sti-designer [(report)]="report" [options]="options"></sti-designer>`
})
export class Example {
    report: Stimulsoft.Report.StiReport;
    options: Stimulsoft.Designer.StiDesignerOptions;

    constructor() {
        this.report = new Stimulsoft.Report.StiReport();
        this.report.loadFile("Dashboards/CusomFontDashboard.mrt");

        // Adding Custom Font
        Stimulsoft.Base.StiFontCollection.addFontFile("Fonts/LongCang-Regular.ttf");

        this.options = new Stimulsoft.Designer.StiDesignerOptions();
        this.options.appearance.fullScreenMode = true;
    }
}

How it works. The engine loads the font before rendering, so custom typography appears in the designer, viewer and exports.