"... Their daughter Maria "Mary" married Herman "Henry" Traugott Flath, my great grandparents. It would be great to share any common information."
I'm not connected to your research, but there were death notices in the local German papers for a Hermann G. Flath (1946). These include fraternal notices placed by the German club he was involved with. I don't own these clippings. There were also multiple death notices, Danksagung and death anniversary notices in multiple papers for a Helene Flath (1917/18).
"Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950).
Gary Rebholz, compiler/editor
Indexing Milwaukee's German newspapers continuously since 2007 ... it's about our German-American culture, not data.