So @Egbert_Williams have you tried doing this with a SMIL file? What protocol are you trying to play these back over? So I can better understand your workflow here. Are you trying to do this through the REST API?
We have an article for both live and VOD streaming with multiple audio channels. You will need to use a SMIL file to present the audio tracks separately. MPEG-TS live streams are supported for input for multi audio live streaming.
https://www.wowza.com/docs/how-to-use-alternative-audio-or-video-tracks-with-apple-hls-streams
If you wish to force one audio channel only we have a module for that.
https://www.wowza.com/docs/how-to-select-audio-data-and-or-video-channel-from-a-multi-channel-mp4-file-by-using-imediareaderactionnotify
Our test players are limited in their support. Please test with a few different players.