Make a file "0_JustSmall.csv" and put your stuff in there (and your stuff only!). You see the one that is loaded up first is used. If you edit the vanilla file you'd have to keep the full file in your mod which is not necessary.
Thanks a lot for the help! I hope I corrected my mistakes.
However, I've run into a further problem which seems to be unrelated to my previous issues:
Whenever I boot up the game (which works fine!), the political map ends up looking like this:
View attachment 121006
Googling and browsing through the various forums has yet to yield any useful information in regards to my problem.
Furthermore I get these logs, maybe they are of any help: error.log and graphics.log
Thanks in advance for any help, it's greatly appreciated!