The short film you're describing sounds like it could be "The Children's Room" written and directed by Joe Russo. It aired on Adult Swim in 2016. The short film is a horror story about two lesbian women in their 40s-50s who adopt a south-asian boy. They struggle to take care of him due to his behavioral issues, and decide to give him up to a mysterious agency. The women try to go about their normal lives, but they miss the boy deeply and decide to visit him. When they visit the agency, they walk down a hallway lined with "statues" of different children from different ethnicities and cultures, but one of the statues start to blink and look at one of the women. It has all the elements you described and it's a very powerful and eerie short film.