Yes, it looks like something is wrong with the data tree structure. I’m guessing this means it isn’t actually joined into a single mesh either, but is a big collection of single faces.
I’m not going to fix your data structure for you. The overall structure of this whole definition looks overly complex and confused.
Also all this lofting and splitting of surfaces, only to create a mesh of triangles in the end is not a good way I think. If what you want is a mesh, better to create the mesh to begin with, rather than going via surfaces.
I’d recommend stepping back a bit - maybe following some tutorials or videos on data trees, then starting again from scratch. Downloading definitions from others can be a great way to learn, but make sure you understand each of the parts of the definition before trying to combine them into a more complex whole.