Maybe it would be possible to name faces created with the face plugin automatically "face_group". The trainsim doesn't like blanks in names.
This is all no problem with more complex models because one renames the groups anyway. But with simple scenery models I tend to take what I get, do a regrouping and that's it.
It is certainly easy to look for spaces and rename groups but you have to think of it in the crucial moments before exporting. And trainsims 'blank' aversion had me frantically looking for all kinds of mistakes before I thought of the correct reason. So, if it's not too much trouble, please ......