I tried making a map editor, and it starts to work quite nice.
https://www.youtube.com/watch?v=vjNXJmDkVHg
After I made the video, I added showing the used palette, render the spritemap accordingly and search for any palette array in code. It does not parse loose PAL commands, but you can always add a bogus array declaration with 15 or 16 colour numbers.
It also makes grading student work a lot easier....