Eva's marriage record does not name her father, and identifies her mother simply as "widow Gassmann".

Eva's child-bearing years spanned at least 22 and possibly as many as 30 years. Her daughter Marianna is recorded as being 7 years 5 months old when Eva and Lazar moved in 1815, so Marianna was born in 1807-08. Philippine married in 1867; the marriage record names her parents as her parents as Lazarus Riesenfeld and Eva Gassmann and gives her age as 31 years, so she was born by this reckoning in 1835-36. Philippine died in January 1918; the death announcement in local a newspaper gives her age as 84 years (so born 1833-34) but her death certificate gives her age as 87 years 9 months, so born 1830-31.

Friedrich Nothmann identifies Lazarus Riesenfeld of Langendorf, family number 2809, as the father of Israel Riesenfeld (born 1801)

On the basis of this wide span, and assuming Israel was her first child, I estimate Eva was born about 1780.