I checked the latest version of the XCC mixer and noticed it can't show intro7b, intro8b, intro8c properly, so I worked a bit on this issue and managed to get the files to show right.
All the other .wsa consist of one normal frame, and the rest are XORed one over the other.
These files don't have a normal frame, the first frame of intro7b should be XORed over the last frame of intro7a.
By editing the frame addresses in the files I could merge the frames into one big file and it showed right in the mixer.

I hope this helps.

hoko.