Log4j 1.2.x is not the problem and Log4j2 is out of the topic.
It is the other way around. As the Cordys platform is extending the log4j 1.2.x library, you must find out the jar containing the following package and classes http://bpm.sihuatech.com/cordys/documentation/onlinehelp/html/javadoc/com/eibus/util/logger/package-summary.html
And this jar must be required here.
As the solution is does not seem open source, I cannot easily google for more info. Is there some cordys SDK or libraries available to you ?