In order for Atelier to provide correct code completion options for the ObjectScript language mode, and for legacy XML export to work correctly, you need to perform a minor edit on the Eclipse initilazation file:
eclipse.ini, in the Eclipse installation directory.
This customization effects the entire Eclipse instance. If you need to work with servers for both InterSystems IRIS and Caché databases, you may want to maintain a separate Eclipse instance customized for InterSystems IRIS.
Atelier Server Connections
Configure a Server Connection