Resolution
The following logs store SiteStudio errors:
1. Most informative is apache error_log: ~cpanel/apache/logs/error_log
2. imaker log: /hsphere/shared/SiteStudio/var/error_log
3. /hsphere/shared/SiteStudio/logs/ss.log
4. /var/log/hsphere/hsphere.log
5. ~cpanel/apache/logs/jserv.log and ~cpanel/apache/logs/mod_jserv.log