Well, I'm no expert either, but I read a lot ...

The CX maps require an unlock code to unlock the enhanced (pedestrian/public transport/etc) routing.
Fast IMG unlocker will not unlock the enhanced data.
Furthermore, the FID on the enhanced data must be changed to (eg 800) to bypass GMA locking.
Then an unlock code (UNL file) can be generated to unlock it.
The unlock code ties the map to a specific device or SD card.

The underlying street (display) map portion of a CX map can be unlocked with Fast IMG Unlocker (as has been already done on the maps available here).


While it hadn't occurred to me, it doesn't surprise me that the UNL file for the Amsterdam map would also unlock the Chicago map -- if they were both files that had had the FID changed to 800.
(The new, slightly surprising observation is that the device probably doesn't care what the name of the UNL file is, it reads the UNL file and now knows that any FID-800 images are unlocked to it. Viva experimentation!) .
(I'm not sure if there are any problems in having multiple maps with the same FID available or available and selected ... but apparently you have both CX Amsterdam and CXNA successfully available, both with FID-800. Again, viva experimentation!)

The requirement to unselect CNNA to enable CXNA is as expected. (The experiment confirms expectations!)

I'll have to get back to you in a couple of days about EL/METRA routing, my Nuvi isn't at hand right now.