I'm using the newest one, version 0.2.16.1
It's not the Civilization IV plug-in though...
Thing is, I don't think that simply using boxes is going to work, I tried it out on a platform, the one on the left in screenshot 15. One simple box, still the exact same problem...
I am very tempted so simply "forget" about the whole arrow bug. I think it's unlikely that people will run around firing at the walls, and if the arrows penetrate, most will properly find it funny and then ignore it, I'd imagine only a few of those who play will actually find it annoying.
From my perspective, it's a matter of priorities, and of course it's more important that the models look good, and making sure you or anyone else won't suddenly fall right through the walls, and that seems to work just perfectly.
So, if you don't mind, I'd rather focus on finishing this set instead of fixing a minor bug.
I will try it out on the next model though, if that work's, I'll redo every collision mesh I've done so far, if not, I'll just continue with the models, with your permission.
But that up for the "bosses" to decide
Edit:
Whee! It seems to work now! Somewhat, I tried to apply texture to the platform (didn't come out as I wanted anyway, could someone kindly link me a tutorial, showing how to texture properly? thanks)
and now arrows actually react to the model, in the wrong way though, since they're stuck in the model. I think I applied a wood material to the model, oops
Anyway, it's great.