My question is that are my UVs okay? How can I optimize it for use in Unreal Engine games? And in the combined view why do my UVs appear almost like a solid object?
You probably shouldn’t have the combined UVs to use in Unreal because it’s going to generate UV errors…overlapping by a ton, outside the 0-1 UV space (pieces extend a bit past the outer border), and they probably also have skewed UV islands. The UV for the one part looks alright, so in importing to UE set the property to maintain the UVs, or at least disable “Generate UVs” for each imported part having a UV map. I’d suggest trying to generate lightmap UVs in UE via the mesh editor. If it doesn’t work, try lightmap UVs in Blender and import those, again disabling “Generate UVs” wherever there’s a property for it.