3D marker - it is a regular GameObject.
Each instance has a world position (marker3d.instance.transform.position).

You can convert coordinates into world position and vice versa:
OnlineMapsTileSetControl.GetCoordsByWorldPosition
OnlineMapsTileSetControl.GetWorldPosition

I see two solutions for your problem:
1. After moving the marker using UnitySteer, you update coordinates of marker.
2. You do not use 3d markers. You create a normal GameObjects, listening OnlineMaps.OnChangePosition and OnlineMaps.OnChangeZoom, and update position of GameObjects.

https://www.youtube.com/watch?v=4ULDER6zJnU

Here's where the assets can be found: https://github.com/ricardojmendez/UnitySteer

The problem seems to hinge around the difference between world coordinates and map coordinates. Markers with steering on them move on their own, but when I move the map or scale the map, the map moves the markers back to where they were. I need to find a way for the steering code to interact with the marker's latitude and longitude instead. This means I need to make sure the distance measuring code is also based off of that instead of world space.

If there's another pathfinding asset that's easier to use with the map assets, I'd be interested to learn of it.

Let me know if I need to explain in greater detail. Thanks!

Actually you can use any assets with 3D markers.
Please explain your problems in detail.
I'll help you solve them.

Do you have any suggestions for either assets that will work with the creation of autonomous markers or for techniques to link the two most gracefully?