A small app written in Qt C++, which converts osu maps back to .osz files. If you want to compile it yourself, you need to compile zlib and quazip first https://zlib.net/ https://stachenov.github.io/quazip/index.html
https://drive.google.com/file/d/1HMOvEAXH98KBiB2vU4xa1HsT00UCz6e6/view?usp=sharing