So I have a material/texture to which the vehicle lights and bits of trim are mapped. I've used aplha transparenct to make the headlight glass see-through as it should be, however there are a few bugs. first you can see the back of the headlight is visible through the crome trim on the grille (both are the same material), even though the chrome part of the texture is not transparent. the rear fascia is also part of this material (and ATM has no trasparency) however the badge and lock (which are alpha mask meshes of a different material) are not visible. Is there any way to correct these errors (ideally without making non-transparent parts of the texture a different material)
That looks like a hole. Hence why you can see the headlight. How does it look with no transparency (or in Blender?) Same for the second. Also how does the material settings look? Usually, if you have stuff overlapping (and some of them are not supposed to be transparent), it's better to use different materials. Using the same material can cause trouble in sorting their transparencies.
With no transparency it appears as it should (no headlight visible, rear badge visible) in that case, would the only solution be to make non-transparent parts of the texture a different material?
If you just need the headlights to be transparent, I advice to create a separate material with transparency just for those. Alpha sorting should be working fine with that.