Here are a few options for a formal, academic-style title, depending on your preferred emphasis:
Option 1 (Concise and precise):
From Disinformation to Foreign Information Manipulation and Interference: Policy and Legal Challenges for European Security
Option 2 (More formal/Academic):
Addressing Foreign Information Manipulation and Interference: Policy and Legal Imperatives for European Security
Option 3 (Focusing on the shift in landscape):
The Evolution of Disinformation: Navigating the Policy and Legal Frameworks of FIMI in European Security
Recommendation:
Your original title is actually already quite strong and suitable for a formal report or research paper. If you wish to make it slightly more polished, Option 1 is the most professional and remains the most faithful to your original intent.