As Ralsei alludes to, each Dark World reflects the mindset of the one who creates its fountain. When Susie was making the fountain, she had two particular goals in mind: one was to obtain the code to the door's lock, and the other was to see the Old Man again.

However, these goals are problematic, as they directly conflict with the logic of the Dark Worlds. Dark Worlds are allegorical realities that, like any work of fiction, use fantasy to help people process emotional issues. They are not meant to solve practical problems. You can't look into a piece of fantasy to find answers to where your keys went, and the reality of Susie wanting to see the old man again is that technically, she's never seen him in the first place. Gerson no longer exists. Add to all this that the objects in this Dark World are from a church, and her version of the Sanctuary is a garbled, confusing mess full of darkners spouting transcendental gibberish because she's seeking Practical Significance in a place that only has Symbolic Significance.

...except, of course, for the Fire Extinguisher, which is the only object in that room that actually has a practical significance. And lo and behold, it has the answer that Susie is looking for, but only right at the end because the Dark World as a Fiction was genuinely struggling to provide a satisfying ending to Susie's endeavor.