I agree that the 4-player adjustment needs reconsideration and suggest an appropriate solution in my comments linked above. But...an easy fix. -1 star for this issue and maybe some other things mentioned by Iammars. But, I don't see these issues as unfixable problems that eclipse the fun of this adventure. If you've got a table of 4, do what's necessary to ensure the quality of the experience until the scenario gets an update (hopefully soon).
I also agree that it's not the best idea to play below subtier on this one. I discouraged it at my tables.
But, aside from those things, it is an open canvas for GM creativity, an exciting return to Azlant Ridge, it has worthy combats that seemed very do-able across my 5 (non-4-player) tables; there is good balance among investigation, RP and combat; and every game was fun and exciting.
If the mark of a good scenario and run is that the players leave the table smiling and wiping the sweat from their brows after a thrilling experience, then this scenario hits the mark.
It's more dangerous than cakewalk PFS, but I don't see it as a TPK scenario in 5-6 PC territory. All my tables succeeded, albeit very narrowly in some cases, which makes it all the more exciting. No deaths. Unconscious/1 round away, yes; dead, no. And with some 4-player fixes, smaller tables can easily come into line.
To me, it seems well-matched against a typical Pathfinder party of 5-6 players and, like every scenario, deserves an appropriate level of GM prep and consideration, especially relating to how to run the final encounter. It's a challenging puzzle trap, and every PC has a job to do. So, nobody should feel left out...but there's also more than one approach.