The principles (gameplay, graphics, …) of AOE IV and its Content Editor are actually great. Therefore I think it’s a shame that both are suffering under the weight of their internal complexity. I do not know if it was the goal of the creators to make the inner workings of the game and the editor so chaotic. Maybe it was a thing of showing of? I don’t know.
In short, by choosing for complex inner gameworking instead of a simple one (the latter proofing true intelligence) the game and its editor are full of bugs.
It’s a shame because Age of Empires IV and the Content Editor could have been so much more.
Good luck however with fixing all the bugs 