However, there were many players guilds and their corresponding guild houses that existed during the game era. The structures and styles varied according to the guild. Some made castle, while others used a shop. There were no similar guild houses.
And, a transition point was standard equipment for a guild house. As for the royal magic library that Shin had visited before, the unusually high level barrier skill was understandable, if it too was installed by a guild. Perhaps, that was also just equipment repurposed from a guild.