SOLVED. Steampunk/fantasy YA pipe worker travels to find cure for mother's illness. [s]

[Tamasen]

I read a book between 2-7 years ago about a young women who lives in a family of artists, except herself, who chose to be a maintenance worker for all the pipes running under their city which is on a beautiful island. Despite her career choice, her relationship with her family is positive and loving. The island gets imports from the mainland on hot air balloons. Other than the pipes being a terrible mess under the city, this is an area of paradise in this world. The book focuses on the protagonist's journey to find a cure for her mom's illness.
*spoilers below*
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*SPOILERS*
The mom's illness seem to have qualities like cancer (which does not seem to be known about in this world), and I think (?) the cure might be some sort of flower that can be found on the mainland. I remember the protagonist travels on a hot air balloon to the mainland, then hops onto a train, which, as it travels through the land closer to sea level, and terrible-looking fog covers the landscape outside the train. The interaction between the protagonist and the mainland officials escorting her seems to be strained, with a lot of suspicion from the officials and questions from the protagonist.

[Ayshe]

Free-Wrench maybe?

[Tamasen]

Yes, that's it! Thank you! I've read the first book and wanted to finish the series.