There is no Peter Fink in the 1798 Grimm census, but there is a Johann Just Fink. His wife's name was Dorothea, and he was born in 1737, close enough to be a match with Peter Fink from the 1767 and 1775 censuses except for the dramatically different first name. With the limited influx of settlers between 1775 and 1798, it seems unlikely that another person with the surname Fink, the same age and the same spouse's first name moved to Grimm. His two sons were young enough to be born after 1775 and married before 1798. Peter and Johann Just were probably the same person or perhaps brothers.
Wife of Child #2 Anna Elisabeth Schäfer Fink, age 20
By 1834, there were no longer any Finks living in Grimm.
Peter/Johann Just probably passed away, as did his wife, and their sons and their families moved to other villages.
Pleve, Igor. Einwanderung in das Wolgagebiet 1764-1767, Herausgegeben von Alfred Eisfeld under Mitarbeit von Sabine Eichwald, Published by the Nordost-Instsitut - 38085 Göttingen, 2005; page 80, family #52.
↑The 1775 and 1798 Census of the German Colony on the Volga, Lesnoy Karamysh, also known as Grimm; Published by the American Historical Society of Germans from Russia, Lincoln, Nebraska, USA; Published date: 1995; family #129 in the 1775 census.
↑The 1775 and 1798 Census of the German Colony on the Volga, Lesnoy Karamysh, also known as Grimm; Published by the American Historical Society of Germans from Russia, Lincoln, Nebraska, USA; Published date: 1995; family #67 in the 1798 census.
↑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.