i have a question: there is a women Albertine Liebenguth, with the same parents, born 1875 Germany. do you know her ?
the next point is, there is a Eugen Liebenguth in the US census with a daughter Elsa. is this your's ? because the mother of Elsa deceased there is a probate curt online.
in Belfort self are no entries for Liebenguth.http://www.archives.cg90.fr/?id=etat_civil