Oscar,
One way I have seen others handle this is to use a different config.json based on the browsers locale:
\jimu.js\ConfigLoader.js
function loadWidgetManifest(widgetManager, e, portalUrl){
function _doLoadWidgetManifest(e){
if (e.name === "Identify"){
console.log(dojoConfig.locale);
if (dojoConfig.locale.indexOf("fr") >= 0) {
e.config = "configs/Identify/config__28FR.json";
}
}
...