Yup, all the file names are exact. I used a chart to match each file name, then checked both 10 times to make sure. Start of layout sounds don't play in any of the three layouts where it's present. A sound connected to a button command doesn't play either. There is also some ambient sound that's supposed to start at Start of layout, but that doesn't play as well. Everything works fine in the .cap but the exe's sounds are mostly dead.
I've been using .62, maybe this has all been fixed since then. I'm not sure I have the patience (and I'm already past the agreed deadline) to go back and figure out what might be causing the bug. The project is a prototype for a publisher and since I planned to make a video anyway, I can use the .cap to make the video since it seems to play everything with no problems and I'll send that along with the game.
I'll of course be using the newer version of Construct for any new projects I do.