If you need to add complex operations to BIRT reports, you have several options. One that is often overlooked is to write the operation in Java and then use the Java code in the report. This is more simple than you’d think.
Instead of creating a “Report” project, create a Java project for your reports. Now you can put the Java code in the same project or a different project and add that second project to the list of dependencies of your report project. Note that this only works if the report project is of type “Java”.
When you edit your code, you just need to save and run your report (using the various ways to run the preview).