There doesn't seem to be any logging on if or where the jboss-deployment-structure.xml was located. However the processors will always look in the META-INF and WEB-INF directories of deployment.
You can enable trace or debug logging for JBoss Modules which will give you a lot of information. You can add a logger in the web console or in CLI. Here is a CLI example of adding a logger at level TRACE.
James R. Perkins