I know that the crossover with the other series with similarities are quite far-fetched due to that Fox Spirit Matchmaker doesn't even has its own fanfiction page but that shouldn't stop our creativities. So I have some other series that look quite promising if they are to coexist in the same universe.
1 Avatar: The Last Airbender
2 Legend of Korra
3 Inuyasha
Here are some examples, if Tushan existed in the Avatar universe, the city will definitely have to go through at least one battle against the Fire Nation, which I personally called the Siege of Tushan. And leading it would be none other but Jinmian, the self-proclaimed the Golden Fire God, who I pictured here as a Fire Nation's general. And of course, the siege ended with Jinmian's death because his nephew, Dongfang Yuechu, helped the Fox Spirit Queen, Tushan Honghong, who he fell in love with, by teaching her the Invicible Claws. Years later, when Team Avatar arrived, they will find that the Fox Spirits are being quite mad at Avatar Aang for abandoned the world when it needs him the most and berating him for it. And by that time, Honghong would already become Susu because of she was assisting the elderly the fight with the Black Foxes, who are Vaatu's servants. And the only person who can fix her might be the Mother of Faces, the spirit who resided near the Fire Nation's village called Hira'a, hometown of Princess Ursa. But until the Fire Lord is defeated and balance is restored, converting Susu back into Honghong for full-time would have to wait.
And that is just one of the many possibilities for this series' fandom and if anyone know more of the series that is largely influenced by the Eastern cultures that can make the possible good crossovers with Fox Spirit Matchmaker, please do not hesitate to post it on.