I thought this mod would only contain some new micro states
Me too.
But since he seemingly wants to be 100% accurate about even minor border changes, I might as well offer my help regarding my country:
These two municipalities joined Finland in 1918 (Repola) and 1919 (Porajärvi)
http://fi.wikipedia.org/wiki/Tiedosto:Repola-ja-Porajärvi.png They were handed back to Soviet Russia in the Treaty of Tartu in de facto exchange for Petsamo, which actually had already been promised to Finland by the Czar in the 19th century when Finland ceded land (Rajajoki/Siestarjoki area with its arms factory/ies) to Russia on the Karelian Isthmus.
In the Treaty of Moscow in 1940 Finland had to cede the green area of Petsamo shown on this map:
http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Petsamo.png/300px-Petsamo.png This area also belonged to the areas Stalin originally demanded before the invasion. The red area is an area not technically forcibly ceded to the Soviet Union, but instead it was sold away in 1947 so Finland could keep some of the German equipment it had acquired during WWII, instead of having to give it away to the Russians. This area is often incorrectly confused as being a part of Petsamo, but it never was, it had been a part of the Municipality of Inari long before 1920.
And of course there are the strategically important outer islands of the Gulf of Finland, also a part of Stalin's demands in 1939, ceded to the USSR in 1940 and again in 1944.
http://www.luovutettuluonto.net/julkaistavaksi2.gif Suursaari was of especially big strategic importance, and if anything, that should be included in DH or at least your mod. Why? Because whoever controlled it pretty much decided who was getting in and out of the eastern end of the Gulf of Finland. This is why the Red Banner Baltic fleet was locked up at Kronshtadt from 1941 to 1944. Even the Germans launched their own invasion of it in 1944 (Operation Tanne Ost), beginning the hostilities between Finland and Germany.
Not sure if you're going to include such tiny provinces, but since you're doing it in other parts of the worldmap, then I guess why not. In any case I hope this information was helpful.