It's my weakest field, granted, but there's a reason most mods just use the default map with the provinces changed around. Map modding is EXTREMELY finicky. Alter one pixel in the province bmp file, and you're getting guaranteed insta crashes. Minor adjustments require manipulation of several different files, none of which follow the standard scripting of everything else in hoi4. The built in nudge tool is supposed to help you with this, but it's busted to Mesopotamia and back. It might work, but it might also just crash the game. Oh, and good luck finding out what's wrong with the map files. The error log puts out diddly squat in terms of map errors, so enjoy digging through crash logs and xml files idiot!
Your best bet is to find a russian furry who is willing to stop binge drinking long enough to assist you. He'll look at your code, do something inexplicable, everything will work, and he'll call you a moron and leave. The primary drawback of this strategy is that you have to use discord, and you have to willingly speak to a furry. But such is the burden of those who pursue the forbidden knowledge of Johan's Digital Fart Cloud, also known as the Clausewitz Engine.