YA Fantasy split between two main characters a girl and a boy in a future dystopian world. had both human controlled mech robots and hot air balloon colonies. Read 2011-2015.

[Zippy]

I couldn't fit all of the details I remember in the topic header. I borrowed it from the local public library between 2011-2015, I remember I found it in the young adult fiction section in a junction between the kids area and the regular library (I've tried but I can't check my history of checkouts).
the series was fiction/fantasy set in a future dystopian world. I only read the first book but I believe it was part of a trilogy, the cover had at least one hot air balloon on it. the story followed two characters, within the first book they never met but I assume they did eventually in the series. The first character introduced was a boy, both main characters were in their teens I believe, and he lived in an abandoned or run down city and was trying to make money through these fighting matches with Mecha, there was some risk of the machine overtaking the human running it I think? I also think the main character was either especially talented or something weird about him and his connection to the mech. the other character was a girl who lived in a colony of hot air balloons that were attached together with ropes. the people would move around by right rope walking essentially. the girl's dad was a ground person and her mom was from the hot air balloon colony, there were memory flashbacks to the girl and her parents living on the ground when she was little and her mom having her practice walking on the clothing line. something happened to her parents, I can't remember what or how but she ended up in the hot air balloon colony. she mostly fits in and the people have some special partnership with birds especially birds of prey, but the girl has some connection to the mechs the boy character is dealing with and the birds don't trust her because of that connection. the ending of the book has her try to do this special apology dance to the birds that almost works but goes wrong at the last minute somehow. I've been thinking about this book for years and so want to find it again but I can't remember the title or author and I've tried online book searches with no results thank you for any help!

[Cupcakedoll]

This is in my to-be-read pile but the inside flap matches!

[Kris]

The Sky Village (also: "Kaimira") by Chris Rettstatt looks very promising. Lots of details available in the reviews on Goodreads.