I think also that a peaceful expression on a corpse was (and is) a source of comfort to grieving family members, especially in JA's era when there was an emphasis on religious faith.

I looked up attitudes towards death in Amanda Vickery's The Gentleman's Daughter: Women's Lives in Georgian England: "The bereaved were routinely urged 'to submit with the greatest Resignation to whatever the hand of providence inflicts on us, & persuade ourselves it is for our Good in some Respect or other...'" (p. 124, her citation LRO, DDGr Cr (21 Dec. 1762, T. Greene, Inner Temple, London, to his mother. Phrases which abound in the correspondence of the bereaved and their commiserators include: 'we must endeavour to submit to the will of providence;, 'joy and afflictions are both dispensed by the same divine providence, your own good sense will teach you to submit to the one as well as the other', 'who the lord loveth, he chastitheth and scourgeth', 'whatever is, is right'" (The Gentleman's Daughter, p. 319).

Fortitude, resignation and faith in providence were generally considered to be the best ways to help the bereaved through their grief, and JA clearly followed those popularly-held views, writing that “as the most acceptable proof of love to the spirit of her departed mother, she [Fanny] will try to be tranquil and resigned, (Le Faye, #59), although she did not insist on ‘enforced resignation’ and shows understanding and sympathy towards Lizzy, one of Edward’s daughters, “one's heart aches for a dejected mind of eight years old” (#59).

As an aside, the description in #60 of the amusements designed to comfort Edward and George is one where I always think "Well done, Jane!", because I can just imagine how she comforted the poor motherless boys, in exactly the right way. Although JA did express some distaste for the state of lying-in and, on hearing of her niece, Anna's latest pregnancy, commented, "Poor Animal; she will be worn out before she is thirty", I think that from reading descriptions like the one in letter #60, and also the descriptions about JA's treatment of children in Caroline Austen's memoir ("Her charm to children was great sweetness of manner–she seemed to love you, and you loved her naturally in return–This as well as I can now recollect and analyse, was what I felt in my earliest days, before I was old enough to be amused by her cleverness. But soon came the delight of her playful talk – everything she could make amusing to a child”, Caroline Austen, My Aunt Jane Austen) she would have made an excellent mother.

"We do not want amusement: bilbocatch, at which George is indefatigable; spillikins, paper ships, riddles, conundrums, and cards, with watching the flow and ebb of the river, and now and then a stroll out, keep us well employed (#60)

"Now Jane rose magnificently to the task of comforting the two boys. She was too sensible to expect them to pine and grieve or listen to psalms and sermons more than could possibly be helped. Instead, she made paper ships with them, to be bombarded with chestnuts, and organized card games and spillikins. She thought up riddles and charades, and best of all went out on the river with them to see a battleship under construction, allowing them to take the oars of the rowing boat a good part of the way. She knew from her own childhood what boys enjoy, and felt instinctively how much better it was to cheer them up with excursions and games than to insist on mourning. It is one of the rare moments in the Austen family history when she was in command; and she did exactly the right thing" (Claire Tomalin, Jane Austen: A Life, p. 209).