Verified, I burned this to a BD-50 and played it back in a hardware player. It’s glorious.

Keep in mind, I do have some general caveats about this sort of endeavor. While all of the streams (video, audio), may be individually UHD-compatible, there can be problems when you try to burn them to disc collectively. There is both a maximum bitrate for the disc, and a maximum number of audio and subtitle tracks. Some UHD authoring tools (e.g. tsMuxeR) will let you blow right past those limits without so much as a warning, and create an ISO which plays fine on your PC, but not in a hardware player.

So while you may be tempted to make a super-ultra-universal UHD with every conceivable audio track and subtitle (er, well, at least that thought has tempted me…), that is not going to happen. Put it out of your mind. You are limited to 32 audio tracks and 32 subtitle tracks, and you may be limited to fewer than that if you decide to pile on multiple lossless tracks.

Me, I played it safe, because I don’t like making coasters. My disc had 12 audio tracks, and only the primary 5.1 track was lossless – the rest were lossy. I also showed a lot of restraint and only included 19 subtitle tracks, but those are far less likely to put your disc over the edge. You could probably be a lot less conservative and still make a playable disc.

Also, burning discs beyond BD-50 capacity is probably asking for trouble. Stick to BD-50 and avoid worries.