The class 52 of the new western diesel pack need some work, the fans on the roof aren't visible and engine room windows are black, I compared it with the class52 for somerset route.
Strange one. Using the provided Blue Class 52, you're right: the fans are covered. I checked one of my re-liveries and the fans are visible albeit black instead of the WSR red. On the windows, the WSR weren't see through but do have 'oily smudges'. The new 52s are pure black as you said. Lack of effort from the texturing department methinks.
This hasn't been fixed yet with the latest update, but I think it's only a texture problem. The livery editor version is correct and doesn't have these problems.