There are plenty of flags that is hard to be determined, mostly are those in communist and fascist ideology. There should be some historical or good fictional design out there. If you want a particular flag in the mod, please make a request with references.

The factors that I will accept a request: (priority in order)

1. The flag excisted historically (e,g, from a historical regime)
   
2. The flag of a historical major party in this ideology
   
3. Fictional flag with legitate design
   
4. Looks good

There are 4 different flags of different ideologies for each nation:
- communism
- democracy
- fascism
- neutrality

here is a preview image of all VANILLA flags for reference
http://i.imgur.com/bZl2SOi.png

you can also find preview image of my mod (maybe not up to date)
http://images.akamai.steamusercontent.com/ugc/269468379398607010/64E683701851716897058697FB530F65862BB46F/



Here is something I wrote about those non-historical flags

Since most of those parties were never reached the government, it's hard to assume what the national flag under their regime is gonna be.

IMO purely using the party flag is not a good solution anyway.

From the real history, most communist regime have a revolutionary new flag design; most fascist regime had more conservative design, maybe because most of them were rised during the war and doesn't really got time to think about it.

The German Third Reich seems to be the only one who completely adopted party flag (with only slight off-centre adjustment) as the national flag. Even though there were a transition when during 1933 and 1935, the old empire flag (back, white and red tricolor) was used in conjunction with the party flag (swastika).

Back to the topic, it's really impossible to "predict" what's the national flag will be when those communist/fascist parties never build a regime to rule the country; or even they had ever climbed to the top, but didn't last long during the war time.

Through the histroy, my guess is if the fascist regime built on long traditional monarchy government, the national flag wouldn't change much (Italy, Japan, Hungary etc.). That's why I believe most european countries including scandinavian countries are in this case.

The Germany was however at the time no longer a monarchy nation (Weimar Republic), that's why they didn't treasure tradition that much. It was like the red revolution of communism, breaking everything old and build things completely new. (It's only my perspective)

With all these being said, since there are no actual historical being of those national flags under communist/fascist regime, there shouldn't be "correct" or "incorrect". The possiblity was really opened, there should be only "plausible" or "implausible".

Luckily there are some wounderful designs under alternative history either looks legimate or purely cool. I think most of the design was under some serious consideration combining historical evidence and the cultural legancies. It's always debatable why using this instead of that. What I do was trying finding a delightful design, or stick with vanillas. To be honest I myself don't care that much about fictional flags of minor nations. For the majoy nation, I would like to pay more attetion to find to best suitable design, even design it myself when necessary. (With last update, I made some scandinavian communist flags on my own)