In Romeo and Juliet Act 4 (scenes 4 and 5), would you comfort the Capulets in their loss?
When I teach Romeo and Juliet, I use this scene to get students like you talking about Juliet's parents' sincerity when it comes to their love for Juliet. The answer to your question would depend upon whether or not you feel they are sincere.
For those students who feel that Lord and Lady Capulet are simply making a very dramatic show of their sorrow, the comfort would lie in the fact that there is now yet another festivity to plan. Lord Capulet does so enjoy a good party, as evidenced in the preparations for and his enjoyment of the ball during which Juliet and Romeo meet.
For those students who feel that Lord and Lady Capulet have suffered an unimaginable loss, the very short answer would be that there is no comforting that family. The loss is so very great, there are no simple words that can be offered. For the nurse, you could point to the friendship that Juliet enjoyed with her and the fact that Juliet took comfort in that friendship. For Juliet's mother and father, you could go back two scenes and look at Juliet's wording when she is imploring her them not to force the marriage with Paris. Though she is distraught, she does appeal to them by professing how much she admires and respects them. Perhaps there is comfort, as well, in the fact that they raised a daughter who was so well liked in their societal circle and sought after by a nobleman such as Paris. I think, though, that the Friar (though he is trying to cover his own self) has the right idea when he simply weeps with them.