since late 2017 early 2018 the game, for me, kept crashing after finishing avenger defense. it was after some update 2kgames or fireaxis did. to get the game to keep playing I had to turn off all mods and play through defense in vanilla. However, soon after these problems, the game would just crash out to desktop on the intro video of reporters talking about the celebration and I could never get the game to run. after a few days I found out after turning off mods one at a time that it was MCM causing the crashes.
I haven't been able to play a mudded game ever since because all good increased squad size mods require your mcm to work. All I ever wanted was the ability to pick and choose a squad of 8 men and equip them but vanillia only lets you choose up to 6, the last two are random.... bummer.

is there ANY way to go in and manually change the game files in order to let you to be able to pick / choose / equip the last two members of a 8 man squad without mods since I cant use MCM or mods that require it anymore ?

I did used to use robojumpers mod but cant anymore because of mcm requirement.