The posts in the picture look tacked on. I'd use the slim metal posts you see with cable. The cable doesn't match anyway. This example uses some wider parts.

There are structural concerns and waterproofing concerns with rooftop decks/railings that should be worked out in the design process. You will most likely have to make some compromise made now that you are in the construction phase. Best to work things out with you builder and designer, if there is one.

That's an expensive way to completely rot out your new structure very quickly. And maybe get a lawsuit when someone falls off the roof, through an improperly built railing.

I’m impressed by the portapotty location….but seriously, make sure the tying into the structure has appropriate waterproofing. Things get very expensive when it does not.

Are you sure the whole structure is engineered to not collapse? Looks way sus.