Here is a newspaper article that indicates another Koberstein family (Rudolf and Adofena) was in the area.  From the Chronicle Telegram dated April 28, 1933 Elyria, Ohio

This article is in 1933.  Later Freeman Koberstein articles started appearing on June 1948.  I don't believe they are related as Freeman came from Glenwood City, St. Croix, Wisconsin and was listed in the Social Security Death Index.

Here is a start on a database in Ancestra Quest and here is FamilySearch decendancy mode.  Rudolof is listed on the Ellis Island database.  Rudolf ethnicity was Ukraine German and residence was Koyszullen, Germany and arrived in the U.S. on 22 Jul 1922 and he was 19 years old (calculated birth year is 1903 which is in agreement with the Social Security Death Index).  He was a single male and departed from the port of Bremen, Germany.  He is listed with the married individuals Christian (calculated birth year of 1866) and Anna (calculated birth year 1860).  This is very probably the parents of Rudolf.