If you save and then use the eye to see if you have uncovered the whole map on each level and then reload, I have found some areas that are not covered in the maps posted or within a lets play. Currently, trying to figure out how to get in the south corridor on the main level of the Temple Moon and there's a corridor I cant reach on the third level to the west. Not sure if these are left over from development or if you can actually get to them some how. Any insight from those that have played this? Thanks!

Yeah, there are portions of which you couldn't access normally, not sure really. Some are just for the purpose of 'storing' enemies for traps & some are completely useless empty spaces.

You must put the SECOND COIN in the first hole of third level to open WEST AREA.