Their faces like yellowed mulberry leaves after autumn; their waists like tender willow-withes before spring.

Yellow leaves and bending willow-withes: faces drained of colour, bodies with no starch left in them. 似 is sì.

The heir-apparent's legs went weak, scarce able to lean on the mourning-staff and perform the full rites of grief;

儲君 is the crown prince. The 喪杖 is the mourner's staff, carried by the chief mourner at a Chinese funeral partly as ritual and partly because grief is supposed to have left you unable to stand. Here it is doing genuine structural work. 盡哀儀 is to complete the observances; 盡 is jìn.

the senior attendants' souls flew off — how could they don the ridged cap and keep the rites of filial duty?

侍長 uses zhǎng, the senior attendants. The 梁冠, liáng guān, is the ridged ceremonial cap worn for formal rites; 冠 here is the noun, guān, not the verb guàn.

The consorts stumbled and fell; the serving-maids reeled and swayed.

欹斜, yī xié, is to tilt and totter.

The consorts, stumbling and falling, were like withered lotuses toppled by a wild wind;

芙蓉 is the lotus, and the standard image for a beautiful woman — so a hall of consorts going down is a bed of lotuses in a gale.

the serving-maids, reeling and swaying, were just like delicate lotus-buds knocked askew by a sudden rain.

菡萏, hàn dàn, is the lotus in bud, a deliberately archaic and pretty word. 好似 uses sì. The younger women get the buds; the consorts got the open flowers.

The assembled ministers, struck with dread, felt their bones go soft and their sinews numb.

骨軟筋麻, "bones gone soft and sinews numb," is what fright does to you from the inside.

Trembling and quaking, dazed and dumbstruck,

痴痴啞啞 is dazed and speechless — four characters, two doubled words, and not a coherent thought among them.

they turned the White-Tiger Hall into something like a bridge with its beam snapped through;

A 斷梁橋 is a bridge whose main beam has snapped: everything still standing, nothing still working.

the clamorous mourning-dais became just like a temple fallen to ruin.

鬧喪臺 is the dais of the noisy funeral. The rhapsody ends on total collapse — a temple falling in, which for a state funeral is about as bad an omen as the imagery bank allows.