The two villages you listed are very small, only one person in each village has a telephone. The closest large city is Lezaksk. There are not Korszniaks listed, there is a: Kozyniak, Elzbeita @ Wyspianskiego #16. There is one Kozak listed a Stefan @ Broniewskiego #5.
If you have any other variations of the surname let me know and I will look them up. This is the closest I could find to what you are looking for.
Good luck in your search.