
Hi,
I have only tentative information there. Most is from the book "Mecklenburger in Osteuropa" ( https://daten.digitale-sammlungen.de/bsb00102914/image_1 ):
This mentions that there was a carpenter Andres/Andreas Jahn in Reval/Tallinn in the 1680s/1690s ( https://daten.digitale-sammlungen.de/bsb00102914/image_119 ), but he was not a citizen of Tallinn and I have no idea where he came from.
The Name Jahnke occurs in Mecklenburg, and the abovementioned book lists two persons named Jahnke who emigrated to the Russian Empire in the late 18th and early 19th centuries:
The tailor Johann Daniel Friedrich Jahnke from the town Goldberg in Mecklenburg became a Riga citizen in 1781 (https://daten.digitale-sammlungen.de/bsb00102914/image_244 ), and the farmer Karl Jahnke from the village Kuckucksmühle in Mecklenburg emigrated to Bessarabia in 1806.( https://daten.digitale-sammlungen.de/bsb00102914/image_516 ).
Regards,
Eike Anderson