concrete ceiling anchor: how much weight can it support?
It would be very difficult to say without knowing the exact company and part number. I found reference to something that might be similar here:

https://www.ccinetwork.com/p-39-38-sanko-shorty-drop-in-anchor-box-of-100.aspx

The info sheet says 2,200 to 5,500 pounds, but again, I wouldn't mount anything expensive or dangerous in them without a lot of stress testing. It would probably be worth bringing in a contractor to take a look and give you some kind of idea. 

Drop ceilings don't weigh that much and it sounds like the weight was distributed over a lot of these anchors so that would suggest to me that they are not designed for heavy loads.