It’s likely that an ENT episode based around Cardassians might involved lost Hebitan artifacts, or the poet Iloja of Prim. As Iloja lived on Vulcan, it’s entirely possible that Iloja was friends with T’Pau or Soval, or other members of the Vulcan Council.
The Detapa Council, Central Command and Obsidian Order would have been around for 300 years by the time of ENT.
When it comes to the question of dictatorship, it’s a question of if the Detapa Council was powerless from the beginning and the civilian leadership was for show like their legal system. Or if the Detapa Council had power and it was degraded over centuries. Since the First Republic was formed by the early 23rd century, and the totalitarian military dictatorship was in full force in the early 24th century.