.wua is not the same as .wad (Wii) or .wbfs (Wii). Do not confuse.
In the past, getting a Wii U game running often involved unzipping a 5GB archive, only to find a folder with 2,000 loose files inside. If you moved one file, the game broke. With .wua, you have one single file. You drop it into your ROMs folder, point your emulator to it, and it boots. It treats the game library more like a standard media library (like MP3s or MP4s) rather than a software development folder. roms .wua
# chdman is from MAME tools chdman extractcd -i game.chd -o extracted.cue aaru create --input extracted.cue --output game.wua the game broke. With .wua