Resolution:
BW 5.11 latest Hotfix (at least HF10 or later) should be installed once TRA 5.8 HF 06 or later is installed. This is because TRA 5.8 HF 06 or later imports newer Tomcat libraries causing BW to be unable to start using Tomcat as the server type.

Error follows.
>>>

         BW-EXT-LOG-100000 A child container failed during start

         java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component

         <<<