The JMX console gives a limited amount of information. Typically this amounts to a few basic statistics like active transaction count, rolled back count etc.
To really get decent information TRACE level logging should be enabled. In your log4j.xml file you should see a few entries like the following:
<!-- Show the evolution of the DataSource pool in the logs [inUse/Available/Max] <category name="org.jboss.resource.connectionmanager.JBossManagedConnectionPool"> <priority value="TRACE" class="org.jboss.logging.XLevel"/> </category> -->
You can enable TRACE for any category you wish, however, when it comes to transactions two categories really are important
Be forwarned, this will produde quite a bit of output, so the more you can narror down the problem area after a few runs the better. Note, sometimes find it helpful to create another appender just to do TRACE level stuff to get a better read of the logs.
Note, if you have a specific issue you can always post it to the JBoss/JCA forum.