The Vine Lashers that are hiding out with the poison bloom hazard plants don't seem to have immunity to the mindfuddle gas. Plants don't have immunity to mind affecting things or mental damage by default as far as I can tell. Some plant creatures do, but Vine Lashers don't call it out in their stat block. I'm about to run this encounter this week, and I'll probably just make the plants immune to mind affecting poisons.
Also, how do the orcs come and go from The Pen safely without setting off the poison blooms or causing the Vine Lashers to attack. They obviously come and go from the place as there are tracks the party can follow right to the entrance. I'm probably just going to add some alchemical elixir that the Sculptor has that he hands out to the orcs as needed. The elixir lasts for 10 minutes and makes the imbiber have the plant trait trait for the duration, which tricks the plants into ignoring them.
Any thoughts or something in the text or rules I'm missing?