As you can see, it can't find the custom character definitions (which were unchanged from the example sketch) as it can't find the file "custchars.ino".
If you make a tab which is not a .h, .c or .cpp file (in other words, another .ino file) the IDE concatenates it with your main sketch and compiles it as a single unit. You don't need to include it. Because of this behaviour it has probably not actually copied this other .ino to the temporary directory, and even if it had, you would then have used it twice, which you wouldn't want.
You are better off sticking to the .h or .cpp paradigm (who includes .txt files into C source?) and work with the IDE on this one.