Richard,

Check if Aaron & Dora are buried with a landsmanshaftn.  These societies were often shtetl based, although one could be with a society of a town they did not come from, the society may be a clue.  Their death certificates may have a clearer spelling of a town of birth.

Since Aaron's mother and his bride have the same surname than they may have been cousins, or from the same shtetl.  Try searching for a town that has both ROSNER and SPANIER residents.
https://www.jewishgen.org/databases/all/