Epsilon is a family of Java-based scripting languages for automating common model-based software engineering tasks, such as code generation, model-to-model transformation and model validation, that work out of the box with EMF (including Xtext and Sirius), UML (including Cameo/MagicDraw), Simulink, XML and other types of models.
EGL supports defining "formatter" classes that post-process the generated code, ensuring it's more presentable:
https://www.eclipse.org/epsilon/doc/egl/#using-a-formatter
I cannot find any way to specify that a given EGX rule should use a certain formatter. I'll see if I can send a PR for this.