Is [the Lisbon Treaty or TFEU] still the primary preventive measure that will stop euro states squabbling to the point of repeating [conflicting bi-lateral treaties, tri-lateral treaties, and alliances of convenience that exacerbated internecine wars for possession of colonial territories]?

Yes.

Sez secular bibble of European "democracy",
Thuc.1.18-21.

Diversity is the key to economic and political evolution.