Well, as for acks specifically -- cimbar itself doesn't really need them, thanks to fountain codes [0].
But I can imagine a reverse (request?) channel being useful, if it had enough bandwidth for the desired application. :)
As /u/ggerganov notes elsewhere in this thread (with some expertise on the audio side -- I can't claim any), the bandwidth of any audio channel is probably going to be pretty bad.
edit: Notwithstanding how viable of an idea it might be, HTTP over audio+video would be pretty neat. :)
[0] https://en.wikipedia.org/wiki/Fountain_code