I didn't know about the pack... What I was referring to was the stock that came with the Lakeside Route. Looking at the files shows me that it's using it's own sound files, and I read somewhere that those sounds were your sounds. Then I saw an update mentioned on your site for the cars you have there, and that lead me to wonder if the RWA Route rolling stock was using old or new sounds.
All of this is coupled with what I am learning (I think) is a game limitation. Namely the way that your sounds (That's where I first noticed it at least) seem to "pop" into the audioscape as I move the camera or as a train passes by. The more I study it in game though, the more it seems like the game may be running out of channels and therefore making a decision to shut off one sound source and turn on your wagon sounds. The big reason I think this is because as the train rolls off to the horizon, your sounds nicely fade away - but by then of course the locomotive is far enough away that all it's sounds are out of the picture.
Something else I noticed today has me confused tho. The RWA 36ft MOW boxcar. If I makeup a consist of 10 GN 36ft Boxcars which I downloaded from your site, get it up to 20mph or so, and hit the brakes, I get this nice smooth screetch of the brakes as they come to a stop. If I do the exact same thing with 10 of the RWA MOW cars, the pitch of the squeal jumps all over the place like the game can't make up it's mind - it's like listening to the brake show equivalent of a vocalist on auto-tune.