So happy to see the tweet, thanks ! You are awesome 
Re: Landscape bug - This is surprising because GetClosestNavigableVolume does a line trace + sweep (via IsDirectPathLineSweep) specifically to ensure that the new vector awarded to the pawn is something it can directly travel to.
If you have a consistently reproducible scenario (if not I suggest setting it up on a new map; easiest way to debug stuff like this), then you can debug the *else if (IsDirectPathLineSweep(CollisionComponent, Location, volumeGuess->Location, hit, bConsiderInitialOverlaps, CollisionShapeInflation)) return volumeGuess; * line to understand why the landscape isn't considered a barrier for auto-correction.
Btw I'm revisiting the plugin and making changes to it after a loong time, so your report has come at an opportune time!