Why do you need to know our motivation? I (and Gornak) don't expect anyone to care about the Moot, most of the time. But when you encounter the Moot in a meaningful way, you/your character should then learn all they can about it, or at least enough to deal with the current situation, whatever that is.
I have never encountered the Veinsormoot in-game in a meaningful way. Hireshmont has mentioned the name once or twice. But so what? I've never had to sign a treaty with the Veinsormoot. I've never had to negotiate a trade agreement with the Veinsormoot. I've never negotiated borders with the Veinsormoot. Yet I do all these things with the various realms that comprise the Veinsormoot. Never once has one of them said "I can't sign that treaty/agreement, you'll have to negotiate with the Veinsormoot."
So, what incentive do I have to deal with the Veinsormoot, or learn anything about it? The members don't promote (except for the occasional mention of the name from Hireshmont). I've never been told to go deal with them. And my dealings with the individual member states have not in any way been impacted, so far as I can tell, by the fact that they are members of this guild. So, considering that I can get everything done that I need to get done without ever having to deal with this Veinsormoot in any way, what incentive do I have to invest the time and effort in learning about it and how to deal with it? As Lorgan even said, the Veinsormoot is actually detrimental to my purposes, as it forces me to deal with the realms as a whole. Which I don't really have to, because the members will deal with me individually.
IMO, if you want people to deal with the Veinsormoot, and make it into something more than just a simple guild, you need to make it easy for them to deal with the guild, and make it to
their advantage. Because right now,
there is absolutely no incentive to or advantage in dealing with them. I don't know how you're going to do this. Game mechanics don't support it for guilds.
