So it seems to work if the items got tagged for inclusion. I tried it with the winter scarf but it didn't work. Anyone know of other costumes missing from the foundry that will import?
Also, I was able to import a Borg, although I haven't purchased one. It doesn't open up the ability to create a borg, but I can modify the costume slightly.
I would say we don't really know why at this point that some work and some don't.
I know that the liberated Borg option in the Foundry costume creator used to be available to everyone (this was a long, long time ago), but at some point it became only available to lifetime subscribers, like it is in-game. We were told this is a bug, but of course nothing has been done to fix it.
The ground costume importer seems to be less forgiving. Hippiejohn was giving me one of his in-game crews for a cameo in a mission, and he was using multiple costumes that weren't in the Foundry, such as Kirk's wraparound tunic. In every case the import would change those costume pieces to something else.
Now, we know for sure that at least 3 space costumes work that are not in the Foundry and at least 3 or 4 do not work. Why that is, I do not know.