A wealth of information about the Twin Spirit Isle is provided here, plenty and enough to enable you to run an adventure set there or indeed to use it as the starting point for a whole campaign.
There are two settlements on Twin Spirit Isle, and each is described in mostly game mechanical terms although there is some small amount of information to present each as a living place in your game as well. They are quite different in nature, but both are interesting and should prove interesting places to visit or even settle in during the course of your game. Characters who hail from them have the option of taking a Cultural Move based on their home rather than a Racial Move when generating the character.
Everything seems to come in twos, there are two powerful spirits here as well. Both are dormant and local religions are based around ensuring that they remain so. However, there are a couple of cults as well, which seek to awaken their chosen spirit and take control of the island in the resulting devastation. This could form the underlying arc to a whole campaign, or you could run a one-shot adventure based on their attempts... but you will have to develop the details of what they are doing for yourself, no actual adventures or even adventure seeds are supplied here.
Overall, it's a useful resource but will need quite a lot of further development before it can be incorporated into your game. The potential is there, and effort will be repaid with an interesting place and plots to further your adventures.