It's not hard to find the promised notes, as they sit upon the mantelpiece in an otherwise empty room. You sit cross-legged in front of the fireplace and begin to read. Near the top is a helpfully-labelled map of Tor Lithanel, including nearby shops for things like food and furniture and, you note with a suddenly dry mouth, books. It explains that with the extinction of House Elwyn, this 'Major House' - apparently referring to the actual structure - has reverted to the crown's control, though the vote it held does not. Also noted are the major powers of Laurelorn that would be most relevant to your project, with carefully polite and long-winded descriptions that you mentally distil into the salient details and winnow into the most promising possible partners.
Major House Thyriolan: Originally from Saphery, and one of the two Major Houses influential in the Temple of Hoeth. They were and presumably still are against involvement with human affairs, but do agree that the waning Waystone network is a major concern for Laurelorn.
Major House Ecthelion: Originally from Saphery, and one of the two Major Houses influential in the Temple of Hoeth. They're less stringently against involvement with the Empire than House Thyriolan, but unlike House Thyriolan they do look down upon humanity.
Major House Tindomiel: Originally from Saphery, and one of the two Major Houses influential in the Temple of... Hekarti? Isn't she a Druchii Goddess? Well, they did vote in favour of interaction with the Empire so they might be a better option for a magically-inclined Major House to bring into the project than the two Hoethian ones.
Major House Fanpatar: The House of Prince Galenstra, a formerly Yvressian House that dominates the worship of Ladrielle. Less scholarly than the previous houses, perhaps, but the Prince did seem open to the idea, practically-minded, and curious about human and Dwarven inventions.
Major House Ellemakil: A formerly Avelornian House, and one that has recently come to dominate the fledgling Temple of Ulric. Presumably they are the House most enthusiastic about cooperating with humans.
Major House Malforric: With the extinction of House Elwyn, House Malforric now dominates the worship of Asuryan. They are also the Warden of the Sun. This makes them second only to the Queen in power, which would make them very useful to get on your side. However, they are possibly the most isolationist Major House in the entire city.