Hi YASHIK,
AFAIK, there isn't a more realistic data than the provided demo data.
I think the demo data is just to get user started. The PDI is provided so users themselves would be able to enter their more realistic data and test functionalities.
Demo data is fine but each company has their own requirements that may differ. I personally found it better to try to enter some data myself and learn from the experience. In actual implementation, it not just the data that's important but also rules on how data should be entered and steps on how they should be entered. These won't come just be looking at demo data or somebody's else rules and steps.
I've also found the forum to be a good place to ask questions when I get stuck.
