My suggestion for guild plot progression mirrors the individual players plot progression system in a way. My suggestion is that when a guild is founded, it is given a small allocation of specialized plots. These plots are each tied to a specific profession, and advancing these professions inside these plots raises that guilds xp in that profession. Additionally, members who raise their xp in a guild’s appropriate plot gain a small coop bonus to their own professions’ xp.
For example, a guild sets down their “builder” plots for an HQ, the builders then build the HQ, the guild gains xp in building and a few extra building plots per level, and the builders gain bonus xp to their profession for work within the guilds plot. Those newly gained plots can be allocated for a larger guild HQ, or establish secondary guild outposts, towns, etc.
Mining can work in a similar fashion- first place a mining plot beacon, mine the contents, then gain additional mine plots and xp. (This idea needs further work!)
Trade districts could be simply a subset of build plots that also gain xp whenever a trade or plinth purchase is made inside it’s influence.
Attack may simply be tracked based on a players individual actions, and could feed a small portion of xp into the “builder” plots so as to provide a second avenue of xp gain besides just building.
Let me know your thoughts and help me expand on this idea a bit! I just have the beginning of a ssystem here, but with your help I think a viable system could come from this.