I don't know, this is the first time I hear of this issue...
Yes, as I said I was pretty sure I had messed something up. As it was, I had simply configured all the mods to install to \Graphics folder. Seemed to work to a treat as it was, apart to this bridge thing. Now that I configured them to install to \AltGraphics instead, the damaged bridges showed up as well. It must have been because there was already some damaged bridge graphics available in AltGraphics, the game reads that folder first, then continues to Graphics, right?
Anyway, your mod works now as supposed to, including bridges
Additionally, I added damaged bridges just by themselves to my JSGME configuration, and can now easily add them to other mods as well: