Multi-byte messages in log files in the /var/opt/SUNWam/logs directory are displayed as question marks (?). Log files are in native encoding and not always UTF-8. When a web container instance starts in a certain locale, log files will be in native encoding for that locale. If you switch to another locale and restart the web container instance, the ongoing messages will be in the native encoding for the current locale, but messages from previous encoding will be displayed as question marks.
Workaround: Make sure to start any web container instances always using the same native encoding.