When system locale is set to Chinese the issue happens.
The MONTH AM PM getting printed in ?? an not printed in chinese.

the output is -
>> ?? 01, 2016 12:12:17 ?? test.swing.LoggerTest test
>> ??: This is a Chinese locale: zh_CN

But when locale is set to english there are no issues.

Here is the sample test case:

---------- BEGIN SOURCE ----------
import java.util.Locale;
import java.util.logging.Level;
import java.util.logging.Logger;

public class LoggerTest {

    private static final Logger LOGGER = Logger
            .getLogger(LoggerTest.class.getName());

    public static void main(String[] args) {

        LoggerTest loggerTest = new LoggerTest();
        loggerTest.test();
    }

    private void test() {

        LOGGER.log(Level.INFO, "This is a English locale: {0}",
                new Object[] { Locale.getDefault() });
        System.out.println();

        Locale chineseLocale = new Locale("zh", "CN");
        Locale.setDefault(chineseLocale);
        LOGGER.log(Level.INFO, "This is a Chinese locale: {0}",
                new Object[] { Locale.getDefault() });
        System.out.println();
    }
}


---------- END SOURCE ----------