not sure what the problem is in... can you show the same model in ZModeler with correct textures/materials assignment? also, point explicitly a model/part/fragment with problematic material, as I thought we were talking about floor carpet, and now we seem to talk about wooden decorative panels, right?
Also, create a sphere/cube object, assign a "problematic" material onto it; move it to a windscreen, so it will be clearly seen in game; then use Modify\Attach to attach sphere/cube object to an existing interior model geometry. thus, you will be sure you are looking to your own modded model.
Finally, add some unique name to your material, It (might be possible) could be suppressed by a matching material file\location found in a different mod.
Summary: unique material name; unique (clearly visible new) object attached to the model to inspect material on; the .mat/.obj looks Ok to me. The only thing is I don't want you to edit TOBJ files manually, neither by any other tools. ZModeler will generate absolutely OK tobj files when export is configured properly.