Ocorreu porque você nao copiou a lib do Firebird para o classpath do ireport
SEVERE [org.hibernate.connection.DriverManagerConnectionProvider]: JDBC Driver class not found: org.firebirdsql.jdbc.FBDriver
java.lang.ClassNotFoundException: org.firebirdsql.jdbc.FBDriver
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at org.netbeans.ProxyClassLoader.loadClass(ProxyClassLoader.java:252)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
[SOLUCAO]
Copie
jaybird-full-2.1.6.jar
para pasta
…/ireport/core