The problem with this scenario cannot be addressed without spoilers, read at your own risk.
the last encounter:
The last encounter is a CR 7 Incorporeal creature. Against a party of 3-4th level pc's who do not have the ability to damage it consistently. The only weapon in the game that does force damage is in an adventure path book and it only works for strength based characters. The ghost killer fusion is still out of sight for level 3 characters and not on the mind of level 4 ones.
And not every single party if coing to consist of two melee sponges and four technomancers with nothing but magic missles at the ready.
It is not like pathfinder where magical weapons are an instant investment, and countermeasures against every single type of creature are abundant, due to an extensive library of single subject splatbooks.
It is hard to hit because starfinder characters cannot boost their to hit reliably and even then, very little damage will go to its effective health pool of 250hp...against a party of 3-4th level pc's
It hits extremely hard and has very hard to resist wisdom damage on its attacks, wich are basically an auto hit everything except a full ac focused Vesk vanguard fighting defensively. Oh and it can spend a resolve to massivly increase this wisdom damage. AND IT FLIES.
The writer needs to understand that putting starfinder characters against apl+3 is extremely challenging of itself, adding incorporeal is just flipping a metaphorical bird.
I apologize if some of the wording comes off as hateful, but it cannot be overestimated how much this scenario is a great of example of :
'Just because you could, does not mean you should'
Ultimate wilderness has had a lot of expectations behind it, sadly the Shifter does not deliver, the Shifter is easy to build and master but it is leagues behind the other classes in almost all departments. A melee Druid with 8 wisdom would do a better job at a melee shapeshifter than the Shifter itself. Hilariously, the best way to play a Shifter, is to not play a full Shifter. This is not to say that the Shifter is terrible, just very plainly average.
The book shines like an Ivory tower, a public playtest would have helped with the numerous errors that this book has and the adjustments it needs, I hope this convinces Paizo to open a Public playtest the next time they release a new class.
Ultimate Wilderness also contains a lot of justified nerfs and errata though rather than cutting out weeds, they torched the entire garden with a flamethrower.
Even after all of these, I have noticed in my time with the book that there are many options in this book that are abusable, even broken.
All in all, Paizo can do much, MUCH better and I know for a Fact that they have had the time to release a full Faq/Errata document on it's release day.
People of the wastes containts a multitude of options for an otherwise rarely visited area of Golarion.
One thing that bothers me is that multiple options hinge on the mana wastes mutant template, whose pros far outstrip the cons, I believe however that all the options granted by this book are fair and reasonable.
Tapping into clockwork cybernetics, primal magic and proximity to the gun capital of the world, People of the wastes is a perfect addition for people who want to make more oddball or even grimdark characters.