The lack of answers ANYWHERE is so annoying. I also don't have any answers as to color or the integers. However I tried changing names from that file and it doesn't work. There are a handful of country names that are located in 'text_l_english.yml' instead of the countries file, which is why Byzantium and Naples weren't messed up for you. Ottomans and Lithuania display custom names. I say partially works because for some reason only about half of the countries display the names you give them, while others retain their original names despite changes. (The 'z_' makes the file load last and overwrite names from the original file.) Editing the original files directly always causes them to display tags (like 3 letter country codes) instead of the assigned text, in my experience. If you wanted to, you could make a client state and give them provinces and name them whatever you like. Include all your changes in this new file only and place it in the localisation folder, leaving the original files untouched. You can't customize your nation's name, unless it's a custom nation. What works *partially* is to make a copy of the localisation file and rename with a 'z_' in front like so: 'z_countries_l_english.yml' What i gather so far is it worked fine in earlier patches of the game but for some reason not in the latest ones. Well I'm having the same issues as you half a year later.

Eu4 change nation name