The game itself is the same on GOG and Steam; I just use the Steam install path if people do not specify, since Steam doesn't make it very clear, and GOG users are more likely to know the install path.
With your save (after I replaced the zero byte inv.b2 file missing from the zip) when I went to the dwarven halls and spoke to Elmer Vignus, I was able to say I was there to pick up the brooch, and then deliver it to Randell.
I did teleport back to Aleroth first, though (used the teleporter pyramid, hoping the other would be near a teleporter pad), to get to the dwarven halls, so maybe that reset something.
