error.log is written, but not defined in logspec.xml
Even though you changed error.log to something else in logspec.xml, CQ still writes both in error.log and the new log file.
Under server/runtime/0/_author/WEB-INF/web.xml locate the cq.logfile parameter, and replace the param-value by your own custom log file. For example:
Until the logspec.xml is parsed during the Communiqué startup, the default behavior is to log the entries in logs/error.log.