I hope you get better and more useful advice soon. Give the forum a day or two. If you post in other AE forums, think about coming back to them all and telling us what worked for you.
Don’t mean to sound mean but this should have been researched and could have been easily tested in the field. How many times you get to go to Paris to shoot?
You will need to determine what is causing the flicker. The mains in Europe are 50 Hertz. If you were shooting at a 60 Hertz variation there will be a noticeable pattern when you step through by fields in an appropriate viewer. You might be able to simply use a field blend function or some time effects. You will need to move one field of illumination to one field of dark. This is easily done if there is little or no motion in the shot. Severe motion will make the effect useless.
You may need to accept and then apply a dramatic stylistic look and feel to all of your night footage.
There is a Stabilize Color effect in AE that can help but it’s not meant for this kind of work.
Again, hope you get more helpful advice, stuff I haven’t had to try yet.
bogiesan