I do not believe the restore point installation method is intended to be fixed.
It is THE FIX to avoid conflicts between mods.
The main restore point requirement is a simple renaming of 1 folder and replacing it with the new one. (example: In the main game folder the WWI module is #DOF. Change to -#DOF and drag the new one from the zip file in.
All else in the zip file is just dragged into the main game folder and overwrite allowed when asked.
CUP can, based on its massive content and number of downloads needed for the entire package, be intimidating.
It was to me but once the leap is taken there is no going back.
One thing for people considering CUP but hesitating, due to huge downloads, to remember is that you do not need it all.
The one module that is mandatory is the first, the Maps.
Then just get what you want.
Like WWI? Get Dawn of Flight. Sixteen new Campaigns already out for this one.
WWI Campaigns Want between the World Wars, get The Golden Age and fly amazing 20s and 30s scenarios, including the Spanish Civil War on accurate time period maps of Spain.
Then comes World at War, the most comprehensive WWII aircraft sim on the planet.
Most theaters of WWII are there for all major and some minor Countries, many nearly forgotten.
From 1946 til now there is the Jet War package, Early jets, Korea, Viet Nam and more modern content.
New Jet War Campaign: Screaming Eagles Over Korea I am not familiar with the Full Mission Builder but it is spoken of as really top shelf and possibly the best ever.
Sort of like going to the market, get everything or just get what appeals to you.