by default Jabref just use the exact content of the author field in the source of .bib file. So I have to use the and keyword every time. It would be great if it can replace the \n character with and, then one can enter author names in multiple lines but in the Bibtex source they remain as it was before ( just like Mendely).
also, there is a custom filed in Persian named authorfa that is used to add Persian names of authors. it is very hard to mix RTL and and keyword together. so adding this feature will improve the user experience for users with RTL language.
what you write in Jabref form when editing fields:
Joni Hersch
Leslie S. Stratton
what you get in Bibtex source:
Joni Hersch and Leslie S. Stratton