Edit:
I took a look at some of those TMOD's and was surprised at how much work I did on them.
To be clear I only built a few myself, the rest were collected from around the EAW world. What I did was fix up r/s issues and improved some skins.
However, most of my effort was building new damage models and making side specific version of the skins, as well as specific TMODs.
On the damage models, you'll notice with vehicles, ground aircraft and ships there are identical main models in multiple slots but different damage models that are quite a bit different. This way when you attack a column of vehicles, aircraft or ships, when you look back you don't see a line of identical destroyed machines. I think I did some train cars too but I can't recall for sure.
Also, as the frontline moves, the same TMOD's will change sides, mostly just a different skin with different national markings but also models of ground model aircraft, vehicles and ships will change.
Not sure if you're aware but you can also make TMODs disappear based on the year. For instance, if you fly over Guadalcanal in 1942 you'll see invasion craft storming the beach but it you switch to 1943-44 the same area is empty.
You can figure out how to do it by looking at the TMOD.dat editor.