Today I installed the current dev build of Rockbox - a2e5d9563f-230325 - on a new (to me) iPod, and inadvertently/unknowingly put a folder containing the tracks from a particular CD at the root level of my iPod's HD instead of one level removed from the root where an .m3u8 playlist file expected it to be. Despite that, the playlist played all of its tracks without problem. But when I tried to Show Track Info for that playlist by long clicking on various tracks in the Playlist Browser and then short clicking on Show Track Info in the resulting context menu, there was a bit of a pause and then the screen went straight back to the track list in the Playlist Browser. However, if I tried to access Show Track Info from the WPS for any tracks played from that same playlist, the Track Info screen was displayed. It was only through trying to figure out what was going on that I discovered that I had put that one music folder in the wrong place.
I'm surprised that the playlist was able to successfully play its tracks, and also that Show Track Info worked from the WPS. I'm guessing that whatever Rockbox did to get the tracks to play, it also did the same thing to make Show Track Info work from the WPS. Maybe it tries finding the tracks via the database if they're not found via the pathnames in the .m3u8 file?