Well, at least there seems to be a text out of the 100 others which does work well

Someone update the OP?
This is in the OP, under installation instructions:
"
CE or CCE QSPs
Extract in the 'assets\standalone_content\' folder
Any other QSPs should either be deleted or the extension renamed to something else if you want to keep them.
Only 1 QSP should be active at a time or the game will refuse to start. "
This has been in the OP from the start, I think? To me it was pretty clear.
But I can see how the "active" part could (maybe) be confusing to some. Maybe the last line should be changed into: "Only 1 *.qsp file can remain in standalone_content folder, for the game to work properly!" (or something like this)?
I dunno but I've seen a lot of questions relating to exactly that, in multiple QSP game threads. Being honest? Most from people who simply didn't read the instructions though... Some absolutely did but just got confused a bit.