As much as I know about the <> in front of the guildname, it shows that the guild is one of the \"old\" guilds, before the new guild creation rules were created.
About the Housing:
One way to let guilds build their own and unique Guild Buildings is to model it in 3D and than send it to devs and they can aprove or reject it.
Becouse usually if guild is large enough to afford a bigger guildbuilding, there is at least one person who knows 3d enough to make a castle or something like that, but this option should be available only to larger guildbuildings, to save time and size.
This way a guild building will be really unique, of course this creates a problem with matching the architecture of Yliakum...
I think that the additional things like walls and houses should be made from blocks that is already in the game (maybe texturing only to match the texture of the guildhall, but it is not essential)