This looks like the right place to start-

https://www.games2gether.com/endless-legend/forum/15-modding/thread/5779-getting-started-with-steam-workshop


Though I'm having a little trouble translating the example for adding heroes to the UnitBodyInspector list, since the example has brokenheroes A, B, and C but the page it says to reference has 1,2, and 3... so there are a couple cases where things could be clearer. Or I'm just being dense.

Thank you!

https://thorbjorn.itch.io/tiled

Tiled map editor for Endless Legends

https://medias.games2gether.com/forums/Pikou/tutorial-modding.pdf

Modding Tutorial PDF

Subscribbed Workshop Files appear to only be located in the steam directory:
/steam/steamapps/workshop/content/
Unfortunately once you have gotten into that folder they don't have their names or even the names of the game they are from, there are just number strings. Folders immediately in here should correspond to the various games that you have at one point had steam workshop items from on your computer, (empty folders if you deleted those items).
Each folder one level down from there should correspond to a different mod:
E.g.: Endless Legends is the folder 289130 (for me at least) and Tiny Traits is the subfolder 549634394. So the full directory (from the steam folder) for Tiny Traits would be
/steam/steamapps/workshop/content/289130/549634394
It's possible there is a listing of these somewhere but I don't know where. I just dug through folders until I saw stuff I knew the names of and knew what games they were from until I found the right thing.