The Windsor you linked seems to have Shimano STI 2200 vs the Mercier's Shimano STI 2300. I don't know if these model numbers make a difference, but the Mercier's components seem newer?

Aside from that, seems like your Mercier is pretty level.

I recently made some measurements by myself so I don't expect them to be perfectly accurate but I used a level to make sure the straightedge is straight.
I also realized that I'm 5' 11.5".

Here is a picture with my measurements in cm. How does it compare to your measurements? Will that 54cm frame fit me?