In this regard I visited the current owners of Mato Kosyk's home in 2010 and spoke with them regarding this matter and followed up with Roland Marti
in Saarbruecken via email afterwards.
From what I can remember off hand about the entire subject, once Kosyk passed, noone was around that could read his works (in Lower Wendish) and his
wife (...or was it his housekeeper?) thought them worthless. Whether she took them with her to South America or sold them/left them is likely a matter
lost to time. Perhaps a visit to the local court could be made, however unlikely to yield results, and find if any record or mention of his effects
was made...again though with being married there was likely nothing to note there.
Your mention of South Dakota is intriguing. What news is of that?
"Avito Viret Honore - Per Aspera ad Astra"