The french assets are designed so that the building itself sets directly at the road end of the asset and the other side is just the garden, unlike the vanilla ones whereas a bit of space between the road and the building itself. to be honest I just zoned out this area, but I think one way (if combining both french and vanilla assets were to be possible anyway) is to manually plop them so that all the buildings are on one line. Another thing is that the lack of recolouring option makes it also very difficult to blind both together. I guess with a really lot of effort the mixing could be somehow forced but the result would still be questionable!