localization | attribute 'locale' does not translate hidden label for day (@duetds/date-picker/custom-element)

[barburak]

Describe the bug
I am using duetds custom element DuetDatePicker in our vanilla JavaScript based project. When I apply the localization settings, everything is translated into German accordingly, but only the "locale" attribute (value "de-DE" or "de-AT") does not translate the screen reader label for days in the calendar. I also tried other locales/languages, nothing seems to get translated - the english description stays.

I appreciate any help.

Here is an excerpt from our code:

import '@duetds/date-picker';
import {DuetDatePicker} from "@duetds/date-picker/custom-element";

...

setLocalization() {
    this.date.localization = {
      buttonLabel: i18n.get("buttonLabel"),
      placeholder: i18n.get("placeholder"),
      selectedDateMessage: i18n.get("selectedDateMessage"),
      prevMonthLabel: i18n.get("prevMonthLabel"),
      nextMonthLabel: i18n.get("nextMonthLabel"),
      monthSelectLabel: i18n.get("monthSelectLabel"),
      yearSelectLabel: i18n.get("yearSelectLabel"),
      closeLabel: i18n.get("closeLabel"),
      calendarHeading: i18n.get("calendarHeading"),
      dayNames: i18n.get("dayNames"),
      monthNames: i18n.get("monthNames"),
      monthNamesShort: i18n.get("monthNamesShort"),
      locale: i18n.get("locale"), // german locale does not work - issue: screen reader label for chosen date in calendar is still english 
    }
  }

(...) 

connectedCallback() {
 customElements.whenDefined("duet-date-picker")
      .then(() => {
       this.date = this.querySelector('duet-date-picker');
        setTimeout(() => {
          this.setDateAdapter();
          this.setLocalization();
        }, 0);
      });
}