I have hit a wall with my WALTER-WALTHER-WALTERS G-Grandmother also. Have you tried searching with German spellings for the surnames (FISCHER SCHREINER WALTHER)? If you know whether or not they were Catholic or Lutheran you may be able to access church records. I was able to get back to my other 2G-Grandparents on my father's side with church records. Even though they may have attended church in the USA the records may be in German but they may hold clues from where they came.
There is a town called Hesse in Alsace. (I don't know what your document is but if it is a US Census then that may be the name of the town they are from in Alsace) I found it by accident a few months ago. Also Alsace was part of Germany after the Franco Prussian War until after WWI so you may find on Alsace, France, and Germany listed for the same person.