How can I explain my park being in a fictitious place like Xanadu, especially since I don't recall anything there related to Brazilian or German culture?
As for going the Big Hero 6 route and coming up with a name like Berlisilia, how are the readers going to understand what I'm talking about if I don't go into thorough background on it? Aren't they going to want to know the history/context of the city? Come to think of it, wouldn't it make more sense to make a movie around this city (maybe a Disney animated film)?
In any case, here's a brief description of San Fransokyo in "Big Hero 6", courtesy of TVTropes.org (under the section "All There In the Manual"):
While not stated in the film, Word of God is that the movie is set in an alternate timeline where, after the 1906 San Francisco earthquake (which, according to the series, happened two weeks earlier than IRL and was the result of a botched experiment, not a natural event), the city was rebuilt by Japanese immigrants using techniques that allow movement and flexibility in a seismic event. Afterwards it was renamed San Fransokyo due to the mix of Japanese and American architecture.
Wouldn't readers feel lost without similar explanations for Berlisilia? In any case, it's all made up and not as fun as putting it in a real location, or at least in a location that's already established, if not in reality, then at least in culture/mythology.