I finally found this one; "The Invisible Foe" (1982) by Gary Kilworth, published in Isaac Asimov's Science Fiction Magazine, January 18, 1982.
The story opens in a southeast Asian city:
Singapore, my adopted city, moved slowly into the path of the day's first rays of sunshine.
The protagonist is a member of a secret organization of aliens:
So it was between the humans and ourselves over possession of the Earth. We lost that mental combat, at the beginning of time, and later had to disappear into remote retreats in woodlands, mountains, and wastelands. Now we are few, but emerging once again. Seeking our revenge. Our ancestors had come, peacefully, from a distant, dying world, beyond the curve of Orion's belt, at a time when our science was accepted as magic. We were called witches and wizards but though we have the ability to change our physical appearance it is a science, not an art.
The casino is intentionally built with terrible Feng Shui:
"Ah, yes," I said, sadly, almost hiding my face in my hands with shame. "Fung Shui."
"You had the geomancer divine... if that's the right expression, divine the correct position and direction for our Grecian casino and then deliberately..."
"I had it built so that it faced the wrong way. The position is all wrong. It's the manifestation of bad luck... unavoidable because it dominates the whole city." It was a symbol of dissonance and it permeated the lives of all those who lived and worked within the sight of this alien folly.
They seek to weaken cities and countries so they can retake power:
"Some of them will move to the countryside — which can't possibly support them. The others to already overcrowded areas, like Changi. There, living will become difficult. Of course we won't clear the city completely — but to all intents and purposes it will be depopulated. They rely on this great, noisy animal to keep their economy at the level it is — which isn't terribly high. If people leave the city in great numbers it will weaken the island as a whole."
There have been attempts to destroy the casino:
"Arson. Someone has tried to burn it down twice but it's nothing to do with the gambling..."
"Bad Fung Shui? Some people from the city below? That's a good sign, Chai. It means they must hate it badly enough to risk jail."
(It appears I was wrong about the protagonist being titled "architect," which made it harder to find the story.)
The story can be read in the January 18, 1982 issue of Asimov's at the Internet Archive.