I have a fairly complex projects with a couple of dlls and a few hundred source files. Ever so often Codewarrior looses syntax highlighting (I have been using CW since 2.0 and it has been there for quite a while). Sometimes it is only temporarily (when you restart cw its back again). Sometimes it is persistent (need to clean the codewarrior folder in My Documents).
There are a few known issues with syntax highlighting, like for example if you put a space right after the # in a #define statement it will make the highlighting go away. So
# define FOO 1
would make the highlighting disappear. If you are having specific problems with syntax highlighting I'd recommend contacting Metrowerks developer support and notifying them of the problems; they own the editor code and should be able to help you out.
Also note that the syntax highlighting problem I mentioned above has already been fixed in Metrowerks' code, but it might take a while for the fix to appear in an official release.
I do not know of any kind of log file associated with syntax highlighting.
Have you noticed any pattern for when the problem occurs? Lots of editor windows open? Specific lines added or removed to cause it to happen? Anything like that? If so, you should be able to put together a reproducible case for Metrowerks without having to send them your project.
one obvious problem is that when you are in debug mode and you double click on the method in the call stack (this will open the original file) and make some changes to the original file then the coloring is gone from the debugger window. However, this goes away after the end of the debugging session.
A lot more annoying is when it permanently looses coloring. There does not seem to be a pattern when this happens. We only know that the cure is to delete the Metrowerks folder in My Documents, then its fine for some time again (however, you loose all other private settings).