Lost shining on metal surface

Try removing doubles (merge by distance in blender 3) and then edge split.

Have you changed the spec map at all?

Yep, specular map. Basically, have you gone to the warehouse tab yet?

The differences in where and how the object is shiny, compared to the original, is because of the mesh and how it has been split.
When you export a model to blender, Studio splits it along the edges of the UV mapping islands which is what caused those sharp corners on the RV in your first picture.
When you Remove Doubles or Merge By Distance that removes all of the splitting but this also has the result of the game trying to make ALL edges look smooth and curved.
The RV object needs a combination of both types. The curved metal sections should have the doubles removed but the sharp corners, like the sun roof, should be left split so that they shine correctly.

As far as the mesh goes, if you have an area you don't want to have a sharp edge then use remove doubles if you're using a version of Blender below 2.80 (press W) or merge by distance in a version higher than 2.80. Press alt + M to bring up the merge menu.

If you have an area that you want to have a shar; edge then you need to mark the edge sharp and then use the edge split modifier. You can also select the edge and press V to split it (for versions of Blender above 2.80. Not sure if pressing V works for lower versions). 

Blender has trouble shading edges when you have connected faces going in opposite directions. Here's an example of what I mean. The instructions in the image are for Blender 2.78 but other versions of Blender have the edge split modifier so don't worry about what version you're using. The instructions in the image aren't complete either. You'll need to enter edit mode, hold alt and select an edge loop, or shift + alt to select several edge loops at the same time, mark them sharp, then enter object mode and use the edge split modifier. Be sure to uncheck edge angle or all of your edges will be split. 

Or, as I said, you can select an edge loop and press V. And again, pressing V may not work in lower versions of Blender. I'm not sure. 



To re-iterate. If you want a smooth edge then remove doubles or merge by distance. If you want a sharp edge use the edge split modifier or select the edge and press V.

The specular is responsible for shine so you'll need to make a specular. It's not that hard. I wrote a lOoOoOng tutorial here that covers making a specular. It starts at step #79. Please note that it's for a CAS item and covers making a specular mask. You will not need to bother with the specular mask for objects; it's just a CAS thing. And my tutorial involves the use of the specular picker which is the most amazing invention mankind has ever seen, imo, haha.

You'll also need to make a bump map. That isn't hard either and the tutorial I linked covers that, as well. You can take the original bump map and just make the whole thing a solid grey color if you want but don't leave the original bump map of whatever you cloned. You'll get weird lines showing up on your item if you do. I encourage you to make a "real" bump map. It'll improve the look of your mesh quite a lot.

You should be able to export the existing spec from the object you cloned (reclone it) and import it into your package. As for how the images look; the spec will be either grey, red, green, or blue (or patches of those), while the bump map is a lighter grey with darker patterns and lines.