Look here regarding problems getting VanillaMod to work or to verify installation

[FactionHeir]

This is the correct file, yes. It is odd that Mongols appear at turn 3 for you though, since this file only has references to turn 1 (date 2, commented out, thus inactive) and the real date.

That suggests that either your descr_events.txt is in the wrong folder or your bat file to run VM points somewhere else.

Can you make a screenshot of your M2TW directory (where your medieval2.exe etc are) and of your VanillaMod\data\world\maps\campaign\imperial_campaign\ folder for me please and post the links to them here? (use any uploader, like imageshack)