A few questions about static objects and their textures

Spawning an object from a map that is not the current one will cause it to have missing textures. For example, I'm trying to spawn a jungle rock building in east coast:


To fix this, we can copy the .dae, the .materials.json and the textures used for the object's materials, modify the paths in the .materials.json and paste all that in a east coast subfolder. It works:

I'm guessing this happens because when the game loads a level, only the current level's zip file is loaded. Therefore spawning a .dae works, but the currently loaded .materials.json file(s) most likely don't have mappings for this object's materials, which explains the missing textures. Is this the case?


However, the rules seem to change when it comes to self made objects.
To begin, in my mod folder, I put a zip file containing a mirror folder hierarchy of east_coast_usa in which I put a .dae, a .materials.json and a .dds. It works as expected:



But then, I tried spawning the same object in another map and it works. The only drawback is this warning. After failing to spawn the fort in east coast, why is this working?



That said, this is good news because I'd like to be able to spawn my objects in any map. And this is why I tried the following. In my mod folder, I put a zip file with one subfolder unrelated to any level in which I put all the object files. The result: the object still works in all levels at the expense of this warning.



Is this technique reliable? Am I blatantly missing something regarding static objects and textures? Help would be greatly appreciated.