Dear Raouf Ben Hassine,
After sometime, I still thinking that, If we (as a beginner) intended to using jBPM for our own projects then separating component installations is worth a try. When I wrote this article, we were in the progress of integration jBPM for a pilot project, but for some other reasons, we had to using the Activiti for that project. I haven't experiment with jBPM 5.4 since then. That means, for your question, I don't know the answer.
Thank you,
- Quang