Corpsefall Life Cycle
Working with ideas Valadaar posted - I suggest the following time line for an extended campaign or stay in Corpsefall:
0-5 hours after impact: Dust settles, perhaps half burying the corpse. Griz and Renders would be well on their way.
6-12 hours: Griz and Renders begin consuming the remains. Naturally the Griz would be farming it for useful by-products (bone, leather, maybe some tasty gland full of "nom-noms" the baby Griz like or require). The Renders I suppose would have established a colony and proceed with their natural life cycle.
1-3 days: The Griz have left or are leaving, the meat is mostly rancid and the smell overwhelming. Visitors to Corpsefall not immune to this kind of environment would be at least feeling queasy. Bone slugs now start to arrive, hatch or whatever. Render - Bone Slug conflict ensues over the choicest remains.
3 days to 1 month: Render colonies well established, Bone Slug infestation is extensive. Many tunnels network through bone and flesh. Some maybe collapsing, or huge chambers of fetid flesh have formed, maybe some filled with pockets of poisonous gases.
Fungal Forest Stage
1 to 6 months: Most of the corpse is covered in a variety of molds and mushrooms. As a game playable stat, assume that the Forest grows at a rate of 1% a day. So as an alternative this stage starts when 30% of the corpse is covered in fungi. Assume most corpsefalls occupy approximately 250 sq. miles.
Sometime in this stage the body would likely bloat and explode in a rain of rotting meat, spores and other disgusting gizzards. By now most Render colonies are collapsing and moving off to the next meal. Bone slugs and fungi remain - any non-native would not only become ill but also contract one of several diseases, growths or fungal infections. The bloat could last a few days leading up to the last stage.
Corpse Swamp Stage
6 to 12 months: The rotting remains would now be nothing but a sickly grey ankle deep goo or stinking rotting biomass. Whatever bones remain stick out of this mess and a cloud of poisonous gases forms a mist that shrouds the corpsefall. Entry into this is deadly for most creatures, although it does not affect the Bone Slugs.
After a year or two the remaining bio-matter has vanished into the sand leaving whatever bones the slugs haven't consumed exposed to the sky. Eventually they would also vanish.
"Corpsefall never strikes in the same place twice, well...uh, once in while, actually more often than you think."
At the stated frequency of one or two Corpsefall a day, it is inevitable that an impact site will be hit again. This is unlikely within the first stage, however within Fungal Forest stage there is a growing chance the forest is destroyed in a new Corpsefall, this is roughly 5 to 30% depending on its age. From the time a corpse swamp forms until it is reclaimed there is an increasing chance of about 5% a month. Only a third of Corpsefalls make it to the swamp stage and even less are reclaimed.
This way the GM can have a reasonable stay in Corpsefall with some variety in the topology to work with. For a longer stay the players will have to deal with a changing landscape every couple of months.