@MichaelWright , the new Dual Calendar was discussed in the 1H2023 Release Q&A for Learning on May 11, with some nice screenshots. If you were unable to attend that webinar, you might benefit from watching it. In the presentation, SAP explained that, when enabled in the Platform module, Learning users or admins who have their locales set to Arabic or Thai would see two rows of numbers on the Calendar Picker pop-open window when they select a date field within the Learning module. The first row of numbers would be the dates for the Gregorian calendar, and the second row of numbers would be the dates in the secondary calendar. The screenshot example they provided was in the Completed Work menu when you click inside the When Completed filter box.
But I think that users and admins will only be able to see the secondary calendar numbers if their locale is set to Arabic or Thai.