I think it would be neat if they were not just another Golem unit. Perhaps Gargoyles are Golem creations gone wrong, in which the charms that animate them have gone awry. The imperfection of these Golems has relegated them to artwork and manual labour in the city. But when the city is in peril, their Luchuiurp masters have enough control to issue one command, "Gargoyles, heed your city."
In terms of mechanics, I think it would be interesting if every golem creation had a finite chance of failing. This could manifest as a golem which fails on completion, or a chance every turn that a golem will fail, at which point production stops. This would model the difficulty of building the largest golems, even for masters of the craft, and reward large cities with high production (i.e., expertise). a failed golem would add a small amount of culture, or revenue, or the like, representing their new use as urban tools. in a city attack, they would be the first to fall, the front line (maybe with some bonuses).
Just a thought.