My suggestion is changing guild monuments with buildings. Only thing that changed is buildings. All other monument functions are same.
As guild buildings are "buildings", you can put furniture, claim rooms and access monument interface from building.
There is 3 types of guilds: Guilds, Sub-Guilds and Religious Guilds
They are same with vanilla guilds. Erect a guild building and its done. You cant build your guild building on another guild claim nor you cant claim on another claim. Larger keeps means larger borders. Can house Sub-Guilds if keep level is higher than 3.
Monument3=Small Stone Keep
Monument5=Large Stone Keep
There is only 2 types of sub-guild buildings. They have same function. Sub-Guild buildings can be placed on Guild and Religious Guild Claims if their building level is higher than 3. Sub-Guild claim is equal to Monument 2 and cant upgrade.
Religious Guilds have a bit different claim system; their claim is optional. İf they claim lands, they will act like normal Guilds(they can house Sub-Guilds etc.). İf they dont claim lands, they can built on Guild Claims. To build it in a Guild Claim, you need at least 1 level higher keep than the church. You can do religious actions at theese buildings.
Administration Table: You can inspect and craft all types of documents here. İf you are a member of a guild and have a guild seal you can impress seal on documents.
Council Table: In general, it is a poll table. You can start and vote polls here. You can also chat while on the Poll screen. To be a elector, you have to sit around the table.
Town Board: You can put up documents on this and other players can see the documents if they inspect it.