Is this maybe a case where you may be mistakenly confusing record in the technical / computer sense, as opposed to record as meant in the legal sense ? Because your three last questions do not make sense in the legal view.
> The real debate is about whether "off the record" text can exist at all, and if so, under what conditions/duration
This question makes no sense, as you what you are asking is "can i not make a record, when i make a record of something to transmit it to someone else"
> Are captions on a video call a text record? Do those need to be retained?
Yes and yes, of course. It's legally a record. Again, this questions makes very little sense legally.
> The real debate is about whether "off the record" text can exist at all, and if so, under what conditions/duration
This question makes no sense, as you what you are asking is "can i not make a record, when i make a record of something to transmit it to someone else"
> Are captions on a video call a text record? Do those need to be retained?
Yes and yes, of course. It's legally a record. Again, this questions makes very little sense legally.