To be fair, we've biased that sample by deliberately seeking out the ones that we feel we can interact with well. We have mostly not interact with the isolationist houses, because time is precious and our expectations of gain there are low, and we don't know how many of them are isolationists out of economic/internal political stances (like Miriel seem to be) and how many of them mix in racial prejudice against humans (like Echtelion does).
This is a general note, and should not be taken as a suggestion for something we should be doing immediately. However, if we want to maximise the efficiency of interactions with Isolationist Houses, then we've got two major options.
These are the major Gods of Laurelorn:
Patron Gods of Laurelorn: Asuryan, Isha, Vaul, Hoeth, Hekarti. The most prominent Gods of Laurelorn. In terms of the Mandela, Isha is in the middle, Asuryan, Vaul, Hoeth, Hekarti, Atharti, Morai-Heg and Mathlann are in the inner ring. All the remaining gods are in the outer, and both Ereth Khial and Nethu are being considered for removal.
The Queen, House Filuan (Isha), Houses Maeglin (Atharti), Nienna (Morai-Heg), Tindomiel (Hekarti), Quendalmanliye, Mardil and Teleri (all Mathlann) are on our side, and they represent some of the most major gods of the pantheon. However, we lack Asuryan, Vaul and Hoethian support, and three of the Isha Houses are against us.
To acquire the most power as soon as possible, the best choices are House Malforric and House Miriel.
Malforric is self explanatory. They have two votes in the High Council or a vote and a tiebreaker, they control the military defences of the Ward of the Sun, which contains the capital of the Eonir. They dominate Asuryan worship and determine the state of the Festival of Games, giving them influence over the Champion, one of the Triumvir. They hold some of the greatest amounts of influence and power in the Laurelorn, second only to Marrisith.
Miriel, on the other hand, is an efficient choice simply because they have a complete monopoly over Vaul. Their control over the Vaul Priest-Smiths means that one of Laurelorn's most major gods is under the control of one house. The fact that their concerns are largely practical in nature is also an advantage.
There are other options for working through the Isolationist houses, but imo these two are probably the most bang for our buck. I'm pretty sure Malforric is going to be very, very, very hard to crack though.