I have a lot of Edelbergs from Rosario and also Cosakov.  You can view my tree at https://www.sarahsgenies.com.   Try different spellings of Cosakov - I also am in touch with living cousins on the Cosakov side from Rosario - some now live in Israel.
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Sarah L Meyer
Georgetown TX
ANK(I)ER, BIGOS, KARMELEK, PERLSTADT, STOKFISZ, SZPIL(T)BAUM, Poland
BIRGARDOVSKY, EDELBERG, HITE (CHAIT), PERCHIK Russia (southern Ukraine) and some Latvia or Lithuania
https://www.sarahsgenies.com