It is very hard to help you, but I will try. You do not know for sure that there was Roman Catholic church in Velike Lasce. There are nomicrofilmed church records .
This is the entry of your Great Grandfather into the USA 9. Andrej Praznik Vel Lasce 1899 25
Andrej's wife was Agnes. She was born about 1876 in Slovenia. I have not found her entry into the USA. From some of my research on www.familysearch.org looks like her maiden name was Agnes Koslar. There was a male stillborn October 31 1908 in Eveleth to Andrew Prasnik and Agnes Koslar.
1910 Census AndrewPrasnik 35 from Austria Agnes34 from Austria Mary9 Minnesota Andrew6 Minnesota Louis3 Minesota Mary Zidar27 from Austria
1920 Census Andrew Prosznik born 1875 Slovenia SpouseAgnes Prosznikborn 1876 Slovenia ChildrenAndrew Prosznik , Louis Prosznik
1940 Census Andrew Proznick born 1875 Austria residence Eveleth City , Minnesota
Notice the different spellings, Praznik 1899 Prosznik 1920 Proznick 1940
Agnes immigrated in 1900. Do not know if she was married to Andrew at that time.