you are doing it right, but unfortunately there is an bug:/ I will fix it, but due to certain circumstances it will take some time.
If you want to do it yourself, you just need to update two lines of code in Localization.js.
line 13:
- en: require('locale/en.json')
+ [LocalizationMeta.default]: require(`locale/${LocalizationMeta.default}.json`)
line 18:
- this._setLocale("en", this.resources.en)
+ this._setLocale(LocalizationMeta.default, this.resources[LocalizationMeta.default])