I think we can put the funeral rumors to bed, unless Corellian funerals are a lot more fun than Earth ones: http://www.dailymail.co.uk/tvshowbiz/article-3494170/Star-Wars-Episode-VIII-films-aboard-mega-yacht-coast-Dubrovnik-Croatia-sign-film-s-main-stars.html
It looks to me like this is some kind of society event. I’d been leaning in that direction anyway since there are almost as many white costumes as black ones. Looks more like evening wear than mourning garb.