This might not be as much help, as I'm not a coder, but here goes:
Are you using the same savegames between revisions? In many (but not all) cases updating to newer revisions breaks savegames or causes strange behavior. (Hint: If you insist on not starting over unless absolutely necessary, watch the SVN logs when updating.)
Also, I've found from personal experience that the maps should be consistently compiled using the same method, or problems result. I'm not sure why this is true, but for me it's something I've found.
I've also found that the .bat file used on windows to compile maps is rather fast, and yes, it is faster than the python file, although for me the python file never gives me errors or malfunctions.
I'm seeing hundreds, if not thousands of these messages when using the compile.py script. I then ran the Compile_Maps.bat and it compiled a few more maps, with only the "Could not load image pk3, searching in directories for images instead" errors.
In my experience I
think this is normal, I've gotten the game to work fine despite the same output when compiling.
EDIT: I'm going to try to upload a new installer shortly, I'll see if I can manage to get a relatively stable build and package it together (for those who want a dev build).