The lists are updated frequently- ... If a guild is repeatedly (~1 month) no longer able to defeat a boss that they previously have been given credit for, then they are removed from the list on that boss until a new screenshot is provided.
As I've said before I do rarely ask around how the current Progression (Farm Status) is.
The list is just as accurate as You (the community) makes it.
Please keep the updates flowing to ensure that the list is Up-To-Date.
I obviously credit a Guild for a Progression kill if it is mainly a Guild effort. It its to hard to know everyones Alts.
If the Guild can't keep the Farm Status I will remove it at some point anyways.