You can "unlock" the Café Théâtre after finished Sequence 2. The Cafe is located on the east Side of the Paris Map. Here a Picture (red Circle)
A performance on the stage is only in the daytime, so come back to the Café Théâtre when its Daytime. Go inside to the left Side (Bar) and Arno interacts (he drinks Coffee)
Watch the currently performance and wait that a new performance starts. When a new performance starts, do really nothing with your Controller. Is the performance over, leave the Bar and the Achievement unlocks.
The Video shows also
Its the same Location but one Floor up.