Eureka! I actually got my act together and fixed this mess (Much thanks to Hagar, Happ, and James)! And what a stupid mess it was...
...So if it can help spare any of my miserable anguish to others, I'll try, for a moment, to give something back and share a few hard learned lessons:
#1). If you replace 3rd party aircraft to CFS in a situation like this, make sure that both their FOLDER NAMES and their TITLES in the CFG files are identical to the originals. I studiously copied the CFG titles, but neglected to accurately reproduce my folder names (Duh...). MB apparently recognizes aircraft based on their folder names as they appear in the CFS2 AIRCRAFT folder, while CFS itself seems to read the titles from the CFG file in the individual aircraft data. This explains why the