I believe that you were contacted by my cousin, Gayle Kuschnereit Crawford some time ago. I, too, am interested in the Kuschnereit family, but run into brick walls all of the time!
In the early 1980s, I spoke with a Rovina Kuschnerait who was an airline stewardess for PanAmerican Airlines. She was/is a Lithuanian and said that her family's faith was Lutheran, going back to the Reformation days of Martin Luther (our Kuschnereit as well as one other I have found have Lutheran roots.) She also said that Kuschnereit was spelled "Kusznerait" (with a small triangle symbol over the 'z')in Lithuanian.
In looking at history, Lithuania and Poland were one and the same country for many years. The area you are interested may well be Lettland...the Letts were staunchly of the reformed faith in strongly Catholic Lithuania/Poland. I have also seen Kuschnereit listed as an aschkenazi Jewish name.
Would enjoy corresponding with you.
Gary Kuschnereit, Midwest City, OklahomaLuTeaPrin@aol.com