I tried your solution but I ran into some problems. Maybe you want to do something different then me. But here is what I achieved with your solution: Following your solution I was successful to export the foliage objects. Now I have many different static meshes in my content view that I can manually place. But what I really want is to basically replace the foliage objects with the individual static meshes at the same position. And it would take ages to replace every single object. Is this possible with you solution to do that?
EDIT: I think I achieved what I wanted. As the newly created meshes share the same origin. So I can just import them all at one and align the origin.
But this creates a new problem. The axes of the objects lie now not a the center of the object. This is very bad, as I need that to create bounding boxes for the individual object.
So again I would be very grateful for your feedback. If you are able to split the foliage in separate objects and have the separate objects then at the same position the foliage was and also have the correct coordinate system for the objects.