I tried again, with the goblins on the rooftops, and this time I did get the award.

I have no mod that interferes with the awards fdonation. (I didn't even know that having mods could disable the distribution) So I still get them despite having mods. I even finished my honour mode run with a party of 9 (all companions except Minsc and Halsin) thanks to the party limit begone mod. I would completely understand if the award were withheld because of this. (I'm pretty sure I wouldn't have made it past Grym with only 4) But I got it nevertheless. So, the Steam award system does continue to work even with mods enabled.