How are "active members" defined in the lodestone?

[Vidu]

Active members are simply all the members the FC has at the moment - the description is a bit missleading, because acivity isnt being tracked at all. Once someone is a member of an FC, they're counted as an "active member" as far as the lodestone is concerned, even if they dont log in for the next 3 years.

The german lodestone is less missleading here, simply stating "Number of members".

[Vidu]

Odd. I wonder why the German version has different wording. It indeed does have a different connotation.

Different (localisation teams), as always, would be my guess. I'm not sure if the lodestone works as ingame text, as in: being translated from japanese into other languages, but if thats the case the person translating the english version might have interpreted the original japanese a certain way, while the person translating the german version interpreted in a slightly different way - pretty common when translating stuff, since words can often not be directly translated but need to be interpreted.
(Can be quite funny sometimes to compare an english and a german translation and see how different they can be...)