Food for thought
Hi ! 
I’ve been a long time (lurking) watcher of thread and figured I’d say hi and put in some input on your system thus far 
I think one of the next steps to truly level-up your AI system would be to add cooperative AI goals for AI to accomplish certain tasks they could not do by themselves. You can for example have:
- Have 2 AI work together to push up the other AI to a previously inaccessible ledge.
- Detection that a fellow AI is in trouble than seek out & protect it using a swarm/hive-mind type behaviour e.g. a medieval game where all the AI with shields lock into each other when a arrow-storm is upon them
- A physics based object is blocking the path to an objective and the AI can work together in numbers to move the obstacle.
- And much much more
I believe another improvement you could make and which would be pretty straightforward to implement, would be the ability for AI to recognise edges of an object when path-finding and depending on whether it is above or below, decide whether to climb up the ledge or drop down the ledge/hole to the level below.
Just for giggles you could perhaps make an ant colony AI path-finding system to allow AI to allign themselves into structures to get to previously inaccessible heights e.g. making a human pyramid/ladder/slop.
Food for thought
[HR][/HR]
Moreover,
Have you heard of Kythera AI? I’ve been following them since Umbra was first announced as a showcase piece on Crydev.net back in the day 
Star Citizen now uses their middleware as well
Anyhow,
My point to all of is that you might be able to gain some new ideas for your own AI path-finding system and perhaps also work out ways to make improved versions of features within Kythera AI for Unreal Engine 4.
Some interesting Case Studies you should consider reading:
[HR][/HR]**
P.S.** How’s things going with your AI pathfinding system by the way, I hope all is well?