screen.dds are the common names for sp maps but for mp maps, you'll need to name the loading textures like this:
Chisinau_loading 1or2.3 4...dds
otherwise, the textures wont be uploaded on cojmodding.
You can put any texture to replace the loading screens but you need to give it the trk's map name then loading220.127.116.11.18.104.22.168...dds
Look this tutorial for loading screens:
I'm not sure to understand what you mean but i can suggest this.Chisinau_map.dds is empty? Because is load only Taos Pueblo screens 1-6...
Pick any map.dds in another map then put it into your map folder and rename it with your map name.map.dds.
I dont know what you've done with your map but mixing maps is causing wrong attachements to other maps scripts cause the map scripts are still linked to the map settings or any other chromed tool.
So make sure that you dont load scripts from another map inside chromed.
Edit the scripts and replace them manually outside from chromed.
There's a tutorial about exporting or cloning entire maps: