Cryptix, all the information is known to me. I have what may be one of the only map tools. What it does is it searches through the ARM files to get the full correlation set. This set links the map index (Twinleaf = 411) to its encounter rate data, scripts, text, and event data. The map_matrix is used upon calling maps. When you cross that loading line from Route 201 into Twinleaf town, it loads all of this data, and then calculates where it is on that map matrix (just like your image) and then loads the graphical map "map03_27c" which is land_data.narc/0.
Edit: AlphaMap, and its subprograms, and the Alpha-Py Series are not out for release yet.