Really weird.
I used an archiver to un-SFX the file and presto, a folder was created with custom, then names of files, etc. I am going to see what can be done here, see if I can replicate what you achieved.
Update:
OK, I copied the files to \World\Custom\ with no changes and managed to get two CSSSB motors, a Greenliner and a Silverliner. All with no bogies, since the bogie config file had one line kind:bogey. And lots of files in each bogey folder. Hmmm. What I did here was simply copied the bogey folders to \world\custom\bogey\
I wonder if that was right. Any feedback on that, anyone? What I might do is load in a built in bogey to all that stock until I have scrutinised a few bogey files and worked out how to fill the file in properly. New territory for me.
Only one comment; no alternate cab in the CSSSB motors. I suppose that is fruit of the way the objects were constructed, and thus, no attachment points for a cab at the other end of the car?