to reiterate, there really ISN'T such a thing a a "seperate" install. . .
ALL THE SF2 SERIES USES THE SAME CORE FILES LOCATED IN THE /PROGRAM FILES (X86) SECTION. ALL THE DLLS, CATS, EXES, ETC ARE LOCATED THERE.
What you have as "seperate installs" are actually the Mods folders, created by the individual executables, and located in the /Users/Saved Games. . . folder ABOVE the C drive (look at my screen shots above).
So, you have all 5 SF2 games? Which means you DO have SF2 (the basic, plain one, with the Desert terrain)? You can select this terrain to fly on??
Let's try this --
copy/paste the text into a response here, of the EXACT instructions you used to install the terrain, from it's read me.
AND...give us a screen capture of the folder structure of you mods folder (just like mine above.)
also, taking a closer look at your original post's screen caps, I'm not even SEEING a mods folder in the directory tree