JabRef 3.7
Archlinux Kernel 4.8.12-2
Java 1.8.0_112 (OpenJDK)

The results of the ISBN Generator are not following the conventions for author names which leads to references that cannot be resolved in LaTeX.

Steps to reproduce:

1. In menu: BibTeX -> New Entry
2. Change ID type to "ISBN"
3. Enter for ID: 0321331885
4. Press "Generate"
5. The author field content is not correctly formatted:
   Result:
   David Steinberg, Frank Budinsky, Marcelo Paternostro, Ed Merks
   Should be:
   Steinberg, David and Budinsky, Frank and Paternostro, Marcelo and Merks, Ed

The result of the request http://www.ebook.de/de/tools/isbn2bibtex?isbn=0321331885 is:

@book{9780321331885,
  Author = {David Steinberg, Frank Budinsky, Marcelo Paternostro, Ed Merks},
  Title = {EMF. Eclipse Modeling Framework},
  Publisher = {Addison Wesley},
  Year = {2009},
  Date = {2009-01-12},
  PageTotal = {XXIX},
  EAN = {9780321331885},
  ISBN = {0321331885},
  URL = {http://www.ebook.de/de/product/6903954/david_steinberg_frank_budinsky_marcelo_paternostro_ed_merks_emf_eclipse_modeling_framework.html}
}

The entry above is just an example. I tested this with several other books having mutliple authors with a similar outcome.
Obviously the JabRef implementation is not the issue but the service that is hardcoded into the application.