How are you defining your dependencies? and what types specifically are you looking for?
Looking at the repository, it contains the Birt jars and poms. If this is a standard Maven project you are able to declare the dependency as normal. So to reference core-api you should just have to do:
<dependency>
<groupId>org.eclipse.birt</groupId>
<artifactId>coreapi</artifactId>
<version>2.3.2</version>
</dependency>
and ensure the repository is configured correctly in your settings or POM.
Can you post your POM and the trace from the build? it might help diagnose the problem.
Update: Based on your comment, it looks like the issue is that the JBoss Nexus index does not have the Birt projects on it. The dates for the index and both versions of Birt (all artifacts for 2.3.2 and 2.2.2) are both 8th July, and the index is only 83 minutes younger.
Creation of the Nexus index is not automatic, so perhaps the indexer was run before the Birt artifacts were deployed and then published afterwards.