"Death World" seems a bit of an exaggeration.

In the adventure the liason officer describes the jungles of Skrynne as super dangerous: any plant is toxic, any shadow hides a predator, any safe looking passage isn't (p. 255). Is this hyperbole on his part? The only environmental hazard described in the adventure are Terror Cats.

I know the adventure is simply introductory but no mention of flora and no mention of fauna outside of one predator-type?

Has anyone come up with anything to beef-up the dangers of Skrynne's jungles?

I would look at all the dangers of a real jungle and intensify them exponentially. For example for every 2 or 3 hours that the player characters are out of their chimera you could have each of them make a toughness test, if they fail it they are bit by some insect or another and appropriate tests after that are difficult (-10). You could also have them run into a swamp full of 25 ft alligators or a section of jungle where all the plants are covered in thorns that require an agility test to get through on foot or else they do 1d5 damage