Ratatouille the film definitely does not try to present a photo-realistic Paris, but rather a romantic, timeless, surrealistic one with exaggerated textures, diffused lighting, and muted colors.
You can see this represented in the pavilion—in the front, scale, colors, proportions, lines, and angles are realistic. As you move around into the new Ratatouille courtyard, the design gradually changes—colors are more saturated, lines are softer. As your eye moves from street level up and to the “distance” of the 2D facades, the design becomes much more “cartoony”—chimneys become bent at extreme angles, lines skewed in the unrealistic forced rat-perspective from the film, textures are exaggerated, and uneven lines.