Charlotta was born after the 1798 census and married before the 1834 census. This means she was not captured in a census with her biological parents. Unless we find a descendant who has detailed private records, we will probably never know her last name at birth.
Studying the maternal haplogroup of Charlotta's female descendants could help narrow down her maternal ancestry.
Charlotta married Michael Kaltenberger by 1823, and the couple went on to have five children.
Head of the Household Michael Kaltenberger, age 52
Wife Charlotta Kaltenberger, age 55
Child #1 Johann Konrad Kaltenberger, age 25 in 1850, deceased 1854
Grandchild #1 Heinrich Kaltenberger, age 9
Grandchild #2 Philipp Jakob Kaltenberger, age 7 years 8 weeks
Grandchild #3 Johann Jakob Kaltenberger, age 4
Child #2 Anna Margaretha Kaltenberger, age 24
Child #3 Wilhelm Kaltenberger, age 23
Child #4 Johann Adam Kaltenberger, age 13
↑1834 Census of Grimm in the District of Saratov, Russia, dated 2 February 1835; Translated by Brent Mai, Concordia University, Portland, Oregon; Published by Dynasty Publishing, Beaverton, OR, USA; Published 2011; page 11, family #34.
↑1857 Census of Grimm in the District of Saratov, Russia, dated 5 November 1857; Translated by Brent Mai, Concordia University, Portland, Oregon; Published by Dynasty Publishing, Beaverton, OR, USA; Published 2005; page 14, family #36.