In geo-country, regions/districts... names are not translatable.
While this is maybe logical for some countries (to keep for example names in French for France, or German names in Germany, or Brazilian Portuguese names in Brazil...), for countries like India or China it would be better to allow translations in various languages... As for now, they are in English, and for example children in Kerala learn Indian states names in Malayalam (they can not read English names).
Sure you can!
qsTr() is used to mark strings as translatable (https://doc.qt.io/qt-5/qtquick-internationalization.html#1-use-qstr-for-all-literal-user-interface-strings)
For now, in this activity, none of the names are translatable, so you need to update them to be translatable (using qsTr()).
You can also use a special comment (//: translator comment) to help translators knowing to what the string corresponds if needed (for example: https://invent.kde.org/education/gcompris/-/blob/master/src/activities/advanced_colors/advanced_colors.js#L13)