I don't think it's an exclusively human city. He had aelves and humans and some duardin in his Freeguild conversions. And sometimes led by a stormcast Hero or two. I think from my memory it's a city populated with settlers from Azyrheim.
I personally don't mind if the hallowguild was a little bit diverse but dominated by the Imperials of old (like if there was an underground Dark elf/corsair crime ring or a slaaneshi cult, or a couple of dwarfs who live there like they did Altdorf that might be nice
) I just want the states to reform again perhaps this time as Guild cities.
But if I recall correctly chris peach put those elves and stormcasts there as backup, and reinforcements. (not sure about that dwarf)
on his tweet his Storcasts are:
"More reinforcements for the Hallow guild"
and the elves:
"Other Aqshy units to assist Hallowguild in the fight."