I am not sure I have any suggestions really, beyond what I gave you. For such an uncommon name, it is pretty awful to search for. It has obviously been mangled in the transcriptions. The only thing I have found that I know for sure is them is in 1910 Manhattan Census. I think I see their sons in Brooklyn in 1930...atleast the name was spelled right. Anyhow, in 1910 Johanna is listed as Jennie.
I checked Footnote.com hoping to find a petition for naturalization...but came up empty. That would be the goldmine record. I have one in Pennsylvania for a John J. Smutnik from Austria in 1897. I've got one in PA for Andro Novotni, witnessed by Emil P. Smutnik in 1928. Also, in PA, one for a Charles Kremnez, witnessed by Joseph Smutnik in 1903. Another one again for John J. Smutnik in 1903; one for Peter Duricek in 1903, witnessed by John J.; John Sadecky witnessed by John J. in 1903; Albert Lubitsky in 1905, witnessed by Josef Smutnik; George Chladek in 1903, witnessed by Joseph Smutnik; Charles Wisnovsky in 1903, witnessed by Joseph. Unfortunately, I am not getting anything biographical on John J. to indicate whether he could be related to Paul. These were all in PA.
Of interest, is an FBI investigation record that comes up on a Joseph Smutnik, interviewed by Agent Pannell at Akron, OH in 1919; an alleged Bolshevist, whatever that means. It looks like they let him walk for lack of evidence. He was a suspected member of Union of Russian Workers. In the interview he said he was born in Russian Poland. Nothing else biographical, except that he was not married. Interesting anyhow.
There is a Petition for Naturalization in the NY index 1917-1950 for an Ernest Smertnik; a Josephine Smertnik in 1930 Brooklyn, and a Mary Smrtnik in 1930 Brooklyn.
I honestly don't know what else to tell you. I really had no obvious luck searching Passenger Lists either.
Well, I hope I have been of some help. Good luck.