A thought, coming in to this late, is to check the flavor text in the Mistborn books by Brandon Sanderson. Which may point to some detail things to through in.

Volcanic dust on roofs, and roads for example.

I have seen 1600s maps of Port Royal that show turtle pens that look similar to your pens. If you were to add some big turtles in the water that might work.

Looking at your city it seems to me that it is big enough that I don't think I would put in all the buildings. I would put in the important ones but not all. Then make closeup maps of the areas that need it. So if your party goes to the "Inn of the Old Sign" but there is no combat in the area just put a dot on the map with a label. Does that all make sense?

I posted some new maps, this time Cosmographer. The maps are some of the maps for a Traveller adventure called "Deep Shadows" (which I did not write). The original was written with ascii art. Also the adventure is posted in few places on the internet.

At first look the "shaft" appears to be 'different' from the rest of the map.