Maps with preplanning have blueprints and the Lua defines the scale. I do have a Python script somewhere that draws icons on the blueprint depending on the mission file coordinates.

Maps without preplanning would be easier to understand with a proper editor. I usually just teleport to the location. Here are some scripts of mine (requires BLT): https://www.dropbox.com/s/zkcpfpr476vi8wg/debuggers.zip?dl=0

Included scripts:
boxes.lua: Draws the invisible trigger boxes used by the game and adds the editor name as a name tag.
doAttention.lua: Basically turns the player into a guard/camera; draws lines from the player's camera to all detection objects. The lines are green if there is line of sight, red if there is not, blue if there is not but the object is detected anyway because the object itself blocks the view to the detection point.
perks.lua: Various godmode things. Can turn people deaf and/or blind (need to edit the file), draws contours around everyone, increases movement speed, instant interactions and drills, among others.
warp2.lua: Teleport 5 m forwards.
warp.lua: Teleport to the locations given in the file. Need to edit the file obviously to add the locations. It features a pretty decent parser to retrieve the position vectors from entire chunks of mission files, so there's no need to manually strip off the unwanted parts from lines. It also shows the current location in the upper left corner.

Each script activates on button press, so you need to assign hotkeys first.