Have studied this some more, installed QMT (Finally!), updated it with the 2.01 and 4.10m files.
Well, there's a line missing in the QMT_Squadron.txt file.
I've added this one:
r,USSR,78IAP,red,23,78st IAP (Fighter)
Simply copied it from the line above, then replaced 71 by 78, for two instances.
And now, that specific mission shows up fine. (In this example, I-153's replaced by the CW21's
Also, the mission can be hosted successfully now.
Also attached here, the QMT_Squadron.txt file with the fix in it.
QMT_Squadron.txt
Question remaining is, how many more are missing? Failed? Messed up?
We'll find out I guess... sooner or later...