Keep in mind that they are initialy mad for another game. Inside OpenRTS this Faction can’t be implemented the same way, since now, i was more thinking about having the two “entity” as a background story telling than an actual gameplay.
Then to talk more about gameplay, the initial idea to get this Faction inside openRTS following the current engine state, is to have the mesh as army type unit and the yordle as builder type unit, nothing fancy. I was thinking about keeping it simple since I sadly can’t get myself into the code, by expand, this make me unable to extends the engine if some feature is needed. The best i can do right now is reading. Better than nothing 
But, to jump on what @methusalah said, i can expand the initial idea to get a more unique gameplay, this could be interesting for the engine as it will maybe request it to get feature that initialy it wouldn’t had. What you guys think about ?
I’ll brainstorm some gameplay, let see what i can get, feel free to give what you thinked about when reading the first post about them.