Welcome! If you're looking for a Qu Editor, hopefully soon that will be a reality. Keep checking here for the latest updates.
At the moment things are very much a work-in-progress, with the focus on figuring out the format for scene files, and is the biggest area where help is needed in order to provide the most functional editor possible. If you would like to help out, read on!
This project is using Kaitai Struct for documenting the format of files and parsing them; there is an awesome Kaitai Web IDE that makes it really easy to jump right in and modify files. Just download the qu-scene.ksy file from the formats folder in this repository, upload it to the Web IDE along with a scene file from the mixer, and start exploring!
Any of the entries with an id of "unk#" are pieces of data whose purpose is still unknown! If you can figure out what it is (by trying scene files with different settings), open up an issue to describe your findings, or submit a pull request with an updated .ksy file.