Error when mirroring bp splinemesh.

Hey guys,

I am trying to reduce a lot of work hours by mirroring half of the project.

Here is the bp :

346d1069f71cac6ad40d3ccf03d91f1c0d19d092.jpeg

And here is what happens when I try to mirror :


Do you know if I can mirror also the landscape and vegetation placed with foliage tool?

p.s : The streets on the right side are created the same way as left ( I did that first when I started the project , they are not mirrored )