I need to pull the information that is telling the AI to seek a nav link so that I can use that in a factor to make them start a climbing / jumping / crawling etc montage. (to get them to climb over an obstacle, climb up a ladder, crawl under a thing). I know the AI is clearly seeking the nav link, but how can I expose that information so I can use it?
Ai is seeking Nav Link and it working without any changes - just place NavLink, move left and right nodes to desired place. This is simple use of NavLink between two nav areas (separated).
If you need start any action on your pawn, you should use Smart Link. Smart Link is in NavLink under Simple Link. This can be confused - some steps:
Make sure, smart link start and end is same as left and right (on this sample you have jump down but with jump behavior and animation):
https://i.imgur.com/gYqscJE.png
then in level blueprint:
https://i.imgur.com/5vR1Wrn.png
Crowder is my AI name.
As I said, this is sample for jump, but working with other actions too.
Most important - Smart Link is relevant [x] checked.
You can tweak also snap radius and height and broadcast.
This sample is simple but works. I have production functions but they are too complicated to post here, you should make progress with this sample.
Exposing - Ai will use nav link when it will be on the way. Or you should use special behavior tree action or blueprint - op to you - to find specified nav link what is too broad question, but I think, Ai will use it best when it will be necessary and correctly placed on path, nav mesh.
This is my next step. I’m still tweaking my NavLinks like this just placed on level and here a lot of issues - some from engine, some my design connected - not bad, just complicated.
I’m sure (as I know), in theory is possible to use it as child actors or any other way spawn on actors, attached etc. Just we will have problems with smart links locations. It need great code to make left/right and start/end (for smart link) in correct place on the world with dynamic actor - movable or not.
I just back to NavLinks because worked long time on other my project stages, but months ago I found bug blocked from using NavLinks attached, I believe this is solved now, this thread https://answers.unrealengine.com/questions/582746/nav-link-bug-not-nav-link-proxy.html looks fixed, but I not test it yet in 4.18. This is one of reason I drop ai and work on inventory and other things first last few months.
In this sample (thread) I use NavLinks inside other blueprint placed on the world. This is not movable “housing” - just sketch up for test, but it worked as expected, now after fix even better 
You can mark as solved I think.
Enjoy 
This solution was 1st what I thought, but then I looked for way how to do it, very angry few days - for me doc’s are very limited in this matter. But finally it works and I’m glad too
Hey, this is great information thank you so much! Is it possible to get “reached” from NavLinks created as child actors in blueprints? I’m not certain that there’s a “smart link” option in those unfortunately and it’d be really handy to be able to have the nav links attached directly to the actors themselves as child actors.
So, upon creating a “Nav Link Proxy” as it’s own blueprint class I am able to place one as a child actor into the pattern and send an event receive notification via smart link exactly as I needed, thank you so much this has been incredibly helpful!