Hi John, I have a photocopy of a handdrawn map which shows where Krutojarowka was. On the back someone wrote that it is now called "ZARYA - located near Pismenaya and on the Volchya River in Dneipropetrovshaya, about 45 degree angle now Zaporozhye." I don't know if any buildings of the old estate are still standing.
I am a gggranddaughter of Heinrich Thiessen; his son Gerhard was my greatgrandfather. The Gerhard Thiessen family Bible has some info regarding the Harders. Also Gerhard kept a journal for several years and there are several entries referring to the Harders. I have all that in a "story" form and can send it to you per email or snail mail if you'd like. Too long to include here. My email address is on this site.
In short: Barbara Harder, b: 10/28/1867; Gertruda Harder, b: 2/1/1870; Nicolai Harder, b: 11/16/1873, murdered 9/24/1919; Johann Harder, b:2/21/1880, murdered 1/10/1919. I don't know what became of the daughters. What became of your ancestor, Gertruda Wiens Harder Thiessen?