“Gathered around the jussulent cauldron, bubbling over the campfire, the rustling of kexy leaves alerted them to some large presence nearby, and they scattered, each seeking a private latibule.”
What we have here is a collection of lost words; terms that were in common use but then for some reason were just forgotten. There’s nothing about “jussulent” that makes it useless today — it means “full of soup,” and if anything there’s more soup filling pots now than there was in the 1650s. There are still dry, rustling, “kexy” leaves in the forest, and everybody needs a latibule (hiding place) sometimes.
Now, “jussulent” and “latibule” didn’t really make it out of the 1600s, but “kexy” was used until the 1800s. They’re mainstream English words — that is, they’re not from any obscure dialects — and the reason we know anything at all about them is because they were used in print, and appeared in dictionaries (and in fact in the case of the Oxford English Dictionary, they’re still in the dictionary). It’s just that some words get forgotten.
It’s understandable that “scandescope” fell out of use along with the machine for cleaning chimneys that it meant, but as for the rest of them? Maybe it was just a matter of scaevity (bad luck). But really, we should at least bring “kexy” back, don’t you think?