This was tested on 1BC difficulty.
1) When entering the transition area to the Arboretum and Morass, Guillain looks the wrong way when you go near him. This is due to the transitions being mirrored for the Bad Seed DLC.
The same applies to the Collector in these transitions, but it's less noticeable with him.

2) The Morass of the Banished has a lore room where you can find a piece of food. Apparently this food is guaranteed to be malaised, even when playing on 3BC or lower. This is completely fine if it's for lore reasons.
If you keep this malaise and reach the transition to The Nest with full HP and full flask, there is a health fountain (1BC) and you can interact with it to heal your 1 malaise. It would be nice if during the interaction there's a popup saying "Malaise healed" or something. Similar to it saying "Health restored, Health flask refilled" when you're not at 100% or you've used a flask.