Both those models were designed when BPMN 1.0 was available, and the OMG
had no metamodel available for BPMN at the time.
Keep in mind that BPMN stands for Business Process Modeling _Notation_.
The BPMN modeler just gives users the power to apply the notation. It's
not pushing for a reference metamodel of BPMN.
Intalio, and Ismael through a blog post, pushed for the metamodel we use
because it works, nothing more.
There are several initiatives taking place at Eclipse that will interest
you to that regard I think. First, check out the BPMN2 MDT component.
They will implement a reference implementation of the BPMN2 metamodel.
Also look at the STP-IM and the JWT projects. Both can help you with
transforming the BPMN model.
> Any pointers or just developer names are welcome.
My name is Antoine Toulme. You can discuss with me here. I am the lead
for this sub-project.