When establishing  a  sacred scripture (e.g.,  Midrash Va-yosha'),  LC practice for  such things is that if there is  an article in the Encyclopaedia Judaica on  the work, LC  takes the heading from the EJ's article-heading, just  as is done for personal names.  In the case of this midrash, since it is mentioned within an article but does  not  have  an article of  its own, it should be established  in standard romanization.