After doing more research, a quick hack is to do the following:
import esriConfig from "@arcgis/core/config.js";
import * as intl from "@arcgis/core/intl";
export function functionName() {
var lang = intl.getLocale().toLowerCase().slice(0, 2);
var widgetsAssetsPath = esriConfig.assetsPath + "/esri/widgets/";
var legendT9n = `${widgetsAssetsPath}${widget.widget_id}/t9n/${widget.widget_id}_${lang}.json`;
var t9n = {widgetLabel: "Layer List"}; // Default value
returnConfig(legendT9n).then(t9nResults => {
if(t9nResults){
t9n = t9nResults;
}
}).then(function (){
console.log(t9n.widgetLabel);
});
Just something for now so I don't have to define the labels elsewhere...