Two timezones, "Africa/Asmara" and "Africa/Asmera", share the same dislplay names in TimeZoneNames*.java as follows:
            {"Africa/Asmara", EAT},
            {"Africa/Asmera", EAT},

However, TimeZone.getDisplayName() returns a different name if TimeZone.toZoneId().getDisplayname() is called for the timezone.

Test program:
import static java.util.Locale.FRENCH;
import static java.time.format.TextStyle.FULL;
import static java.time.format.TextStyle.SHORT;


    public static void main(String[] args) {
        String[] zones = {"Africa/Asmara", "Africa/Asmera"};
        for (String zone : zones) {
            TimeZone tz = TimeZone.getTimeZone(zone);
            String name_other;

            name_other = tz.getDisplayName(false, TimeZone.LONG, FRENCH);
            System.out.println(name_other);

            name_other = tz.getDisplayName(false, TimeZone.SHORT, FRENCH);
            System.out.println(name_other);

            name_other = tz.getDisplayName(true, TimeZone.LONG, FRENCH);
            System.out.println(name_other);

            name_other = tz.getDisplayName(true, TimeZone.SHORT, FRENCH);
            System.out.println(name_other);


            ZoneId id = tz.toZoneId();
            name_other = id.getDisplayName(FULL, FRENCH);
            System.out.println(name_other);
            name_other = id.getDisplayName(SHORT, FRENCH);
            System.out.println(name_other);


Result:
Heure d'Afrique de l'Est
EAT
Heure d'été d'Afrique de l'Est
EAST
Eastern Africa Time
EAT

Eastern African Time <--- must be in French
EAT
Eastern African Summer Time <--- must be in French
EAST
Eastern Africa Time
EAT


If to.ZoneId().getDisplayName() isn't called, a localized display name is returned for "Africa/Asmera" correctly.